matplotlib-users Mailing List for matplotlib (Page 86)

On 2014/03/02 1:02 AM, ChaoYue wrote:
> Dear Eric,
>
> This solved part of my problem. thanks a lot.
> I think I will revisit this issue when I have time (not promised).
> do you think this could be some feature desirable?

I don't understand what feature you are referring to; evidently I don't 
understand what the problem is, so I don't know what part remains unsolved.

Eric


>
> Cheers,
>
> Chao
>
>
> On Sat, Mar 1, 2014 at 10:39 PM, Eric Firing [via matplotlib] <[hidden
> email] </user/SendEmail.jtp?type=node&node=42956&i=0>> wrote:
>
>     On 2014/03/01 11:03 AM, ChaoYue wrote:
>      > The most correct way might be to design a new colormap with white
>     color
>      > exactly in the middle, however this is very tedious, especially if I
>      > want to try
>      > different colormaps. so the alternative approach would be to set
>     the values
>      > falling in (-1,1) as being masked, so they will be the same as
>     the axes
>      > background color as you mentioned (in our case it's white). My
>     question is,
>      > how can I put this background color (which shows maksed data) in the
>      > colorbar,
>      > by avoiding design a new colormap?
>
>     It's not the answer you want to hear, but I think the correct answer is
>     that you should do this via the colormap, and not by masking the low
>     values.  It doesn't have to be painful.  If, in contourf, you use a
>     diverging colormap with white already in the middle
>     (http://matplotlib.org/examples/color/colormaps_reference.html) and a
>     norm with symmetric limits (vmin and vmax; you can let them be set
>     automatically after you specify your symmetric set of contour
>     boundaries
>     appropriately) then it will be done for you.
>
>     e.g.,
>
>     z = 10 * np.random.randn(20, 30)
>     clevs = [-10, -5, -2, -1, 1, 2, 5, 10]
>     cs = plt.contourf(z, levels=clevs, cmap=plt.get_cmap('PRGn'),
>                         extend='both')
>     cbar = plt.colorbar(cs, spacing='uniform')
>
>     Eric
>
>     ------------------------------------------------------------------------------

Dear Eric,

This solved part of my problem. thanks a lot.
I think I will revisit this issue when I have time (not promised).
do you think this could be some feature desirable?

Cheers,

Chao


On Sat, Mar 1, 2014 at 10:39 PM, Eric Firing [via matplotlib] <
ml-...@n5...> wrote:

> On 2014/03/01 11:03 AM, ChaoYue wrote:
> > The most correct way might be to design a new colormap with white color
> > exactly in the middle, however this is very tedious, especially if I
> > want to try
> > different colormaps. so the alternative approach would be to set the
> values
> > falling in (-1,1) as being masked, so they will be the same as the axes
> > background color as you mentioned (in our case it's white). My question
> is,
> > how can I put this background color (which shows maksed data) in the
> > colorbar,
> > by avoiding design a new colormap?
>
> It's not the answer you want to hear, but I think the correct answer is
> that you should do this via the colormap, and not by masking the low
> values.  It doesn't have to be painful.  If, in contourf, you use a
> diverging colormap with white already in the middle
> (http://matplotlib.org/examples/color/colormaps_reference.html) and a
> norm with symmetric limits (vmin and vmax; you can let them be set
> automatically after you specify your symmetric set of contour boundaries
> appropriately) then it will be done for you.
>
> e.g.,
>
> z = 10 * np.random.randn(20, 30)
> clevs = [-10, -5, -2, -1, 1, 2, 5, 10]
> cs = plt.contourf(z, levels=clevs, cmap=plt.get_cmap('PRGn'),
>                    extend='both')
> cbar = plt.colorbar(cs, spacing='uniform')
>
> Eric
>
> ------------------------------------------------------------------------------
>
> Flow-based real-time traffic analytics software. Cisco certified tool.
> Monitor traffic, SLAs, QoS, Medianet, WAAS etc. with NetFlow Analyzer
> Customize your own dashboards, set traffic alerts and generate reports.
> Network behavioral analysis & security monitoring. All-in-one tool.
>
> http://pubads.g.doubleclick.net/gampad/clk?id=126839071&iu=/4140/ostg.clktrk
> _______________________________________________
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-- 
***********************************************************************************
Chao YUE
Laboratoire des Sciences du Climat et de l'Environnement (LSCE-IPSL)
UMR 1572 CEA-CNRS-UVSQ
Batiment 712 - Pe 119
91191 GIF Sur YVETTE Cedex
Tel: (33) 01 69 08 29 02; Fax:01.69.08.77.16
************************************************************************************




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Sent from the matplotlib - users mailing list archive at Nabble.com.

Hi,

I am trying to insert a .png image to the right side of the plot and
following the code mentioned here:Combine picture and plot with Python
Matplotlib<http://stackoverflow.com/questions/3765056/combine-picture-and-plot-with-python-matplotlib>
Here is what I have tried:

import numpy as npfrom matplotlib.colors import
LinearSegmentedColormapimport matplotlib.pyplot as pltimport
matplotlib as mplimport matplotlib.cbook as cbookfrom matplotlib._png
import read_pngfrom matplotlib.offsetbox import OffsetImage
cmap = mpl.cm.hot
norm = mpl.colors.Normalize(vmin=-1 * outlier, vmax=outlier)
cmap.set_over('green')
cmap.set_under('green')
cmap.set_bad('green')
plt.xlim(0,35)
plt.ylim(0,35)
fig, ax = plt.subplots()
ax.set_aspect('equal')
cb_ax=fig.add_axes([0.85, 0.1, 0.03, 0.8])
img = ax.imshow(np.ma.masked_values(data, outlier), cmap=cmap,
norm=norm, interpolation='none',vmax=outlier)
cb = mpl.colorbar.ColorbarBase(cb_ax, cmap=cmap, norm=norm,
extend='both')##axim = plt.subplot2grid(shape, loc, rowspan=1)
## phlo tree
image_file = cbook.get_sample_data('mytree.png',asfileobj=False)
image = plt.imread(image_file)
phyl_ax=fig.add_axes([0.10,0.1, 0.03, 0.8])
phyl_ax.imshow(image,interpolation='nearest')

Th heat map would be on the left side and the image of a tree will be
inserted on the right side. The above code gives me the required heat
map but the image I am trying to add on the right side isn't
appearing. Can someone lead me as to how I can go about this?

Thanks

>On 02/27/2014 06:58 PM, Jon Roadley-Battin wrote:
>> Good evening,
>>
>> I am at present migrating an application of mine from py27+pygtk (with
>> mpl) to py33+pygobject (gtk3)
>>
>> Unfortunately I am unable to use
>>
>> from  matplotlib.backends.backend_gtk3agg  import  FigureCanvasGTK3Agg
 as  FigureCanvas
>> from  matplotlib.backends.backend_gtk3  import  NavigationToolbar2GTK3
 as  NavigationToolbar
>>
>> Which is is on the examples (
>>
http://matplotlib.org/examples/user_interfaces/embedding_in_gtk3_panzoom.html
>> ) but is also the logical translation from what I presently have.
>> This falls fowl of the cairo issue
>>
>> What I am having to use is backend_gtk3cairo. However this is being
>> triggered
>>
>>  raise ValueError("The Cairo backend can not draw paths longer than
>> 18980 points.")
>>
>> I am generally plotting 7 x-y plots with upto 30,000 points.
>> Now for now I have commented this out from my local install, is there
>> a better/preferred/recommended alternative?
>
>This was put in there because cairo had (at least at the time) a hard
>coded limit on path size, and getting a Python exception was IMHO
>preferable to segfaulting and having the process go away.  Are you
>saying that when you comment it out, it's currently working?  It may be
>that cairo has fixed this limit in the intervening years. Can you
>provide a simple, standalone example that reproduces the error?


Using python33 & pygi-aio-3.10.2-win32_rev18 (to provide pygobject for
windows:)
Using:
http://matplotlib.org/examples/user_interfaces/embedding_in_gtk3_panzoom.htmlas
the baseline provides the following error:

<  File
"c:\Python33\lib\site-packages\matplotlib\backends\backend_gtk3agg.py",
line 52, in on_draw_event
    buf, cairo.FORMAT_ARGB32, width, height)
NotImplementedError: Surface.create_for_data: Not Implemented yet.


This has been mentioned a few times across the ml

Modifying the example to use backend_gtk3cairo

from matplotlib.backends.backend_gtk3cairo import FigureCanvasGTK3Cairo as
FigureCanvas
from matplotlib.backends.backend_gtk3 import NavigationToolbar2GTK3 as
NavigationToolbar


Now the example runs and plots a nice sinewave (as expected). Modify the
script to plot 7 waveforms, 100pts

##############################################################################################################
#!/usr/bin/env python3
"""
demonstrate NavigationToolbar with GTK3 accessed via pygobject
"""

from gi.repository import Gtk

from matplotlib.figure import Figure
import numpy as np
from matplotlib.backends.backend_gtk3cairo import FigureCanvasGTK3Cairo as
FigureCanvas
from matplotlib.backends.backend_gtk3 import NavigationToolbar2GTK3 as
NavigationToolbar


win = Gtk.Window()
win.connect("delete-event", Gtk.main_quit )
win.set_default_size(400,300)
win.set_title("Embedding in GTK")

fig = Figure(figsize=(5,4), dpi=100)
plt = fig.add_subplot(1,1,1)

t = np.arange(0,2*np.pi,2*np.pi/100)
a = np.sin(t + 0*(2*np.pi/7))
b = np.sin(t + 1*(2*np.pi/7))
c = np.sin(t + 2*(2*np.pi/7))
d = np.sin(t + 3*(2*np.pi/7))
e = np.sin(t + 4*(2*np.pi/7))
f = np.sin(t + 5*(2*np.pi/7))
g = np.sin(t + 6*(2*np.pi/7))
plt.plot(t,a)
plt.plot(t,b)
plt.plot(t,c)
plt.plot(t,d)
plt.plot(t,e)
plt.plot(t,f)
plt.plot(t,g)

vbox = Gtk.VBox()
win.add(vbox)

# Add canvas to vbox
canvas = FigureCanvas(fig)  # a Gtk.DrawingArea
vbox.pack_start(canvas, True, True, 0)

# Create toolbar
toolbar = NavigationToolbar(canvas, win)
vbox.pack_start(toolbar, False, False, 0)

win.show_all()
Gtk.main()
####################################################################################################################

This works, its only 100pts for 7 scatters so nothing unexpected.
Modify the arange to create a time array of 30,000 pts.

t = np.arange(0,2*np.pi,2*np.pi/30000)


  File
"c:\Python33\lib\site-packages\matplotlib\backends\backend_cairo.py", line
143, in draw_path
    raise ValueError("The Cairo backend can not draw paths longer than
18980 points.")
ValueError: The Cairo backend can not draw paths longer than 18980 points.


The already mentioned raise to protect against a segfault.
Edit backend_cairo to comment out the check:


    def draw_path(self, gc, path, transform, rgbFace=None):
        #if len(path.vertices) > 18980:
        #    raise ValueError("The Cairo backend can not draw paths longer
than 18980 points.")

        ctx = gc.ctx



7channel, 30,000 pts each is plotted just fine. Zoom rectangle is slow to
render, but this is true for 100pts (so more a gtk3 thing than a cairo and
multiple points thing)

Final script:



#######################################################################################################################
#!/usr/bin/env python3
"""
demonstrate NavigationToolbar with GTK3 accessed via pygobject
"""

from gi.repository import Gtk

from matplotlib.figure import Figure
import numpy as np
from matplotlib.backends.backend_gtk3cairo import FigureCanvasGTK3Cairo as
FigureCanvas   #changed to use gtk3cairo
from matplotlib.backends.backend_gtk3 import NavigationToolbar2GTK3 as
NavigationToolbar


win = Gtk.Window()
win.connect("delete-event", Gtk.main_quit )
win.set_default_size(400,300)
win.set_title("Embedding in GTK")

fig = Figure(figsize=(5,4), dpi=100)
plt = fig.add_subplot(1,1,1)

t = np.arange(0,2*np.pi,2*np.pi/30000)                # 30,000 pt time
array for 7 signals
a = np.sin(t + 0*(2*np.pi/7))
b = np.sin(t + 1*(2*np.pi/7))
c = np.sin(t + 2*(2*np.pi/7))
d = np.sin(t + 3*(2*np.pi/7))
e = np.sin(t + 4*(2*np.pi/7))
f = np.sin(t + 5*(2*np.pi/7))
g = np.sin(t + 6*(2*np.pi/7))
plt.plot(t,a)
plt.plot(t,b)
plt.plot(t,c)
plt.plot(t,d)
plt.plot(t,e)
plt.plot(t,f)
plt.plot(t,g)

vbox = Gtk.VBox()
win.add(vbox)

# Add canvas to vbox
canvas = FigureCanvas(fig)  # a Gtk.DrawingArea
vbox.pack_start(canvas, True, True, 0)

# Create toolbar
toolbar = NavigationToolbar(canvas, win)
vbox.pack_start(toolbar, False, False, 0)

win.show_all()
Gtk.main()
######################################################################################################################



Hope this helps. or is useful

JonRB

On 2014/03/01 11:03 AM, ChaoYue wrote:
> The most correct way might be to design a new colormap with white color
> exactly in the middle, however this is very tedious, especially if I
> want to try
> different colormaps. so the alternative approach would be to set the values
> falling in (-1,1) as being masked, so they will be the same as the axes
> background color as you mentioned (in our case it's white). My question is,
> how can I put this background color (which shows maksed data) in the
> colorbar,
> by avoiding design a new colormap?

It's not the answer you want to hear, but I think the correct answer is 
that you should do this via the colormap, and not by masking the low 
values.  It doesn't have to be painful.  If, in contourf, you use a 
diverging colormap with white already in the middle 
(http://matplotlib.org/examples/color/colormaps_reference.html) and a 
norm with symmetric limits (vmin and vmax; you can let them be set 
automatically after you specify your symmetric set of contour boundaries 
appropriately) then it will be done for you.

e.g.,

z = 10 * np.random.randn(20, 30)
clevs = [-10, -5, -2, -1, 1, 2, 5, 10]
cs = plt.contourf(z, levels=clevs, cmap=plt.get_cmap('PRGn'),
                   extend='both')
cbar = plt.colorbar(cs, spacing='uniform')

Eric

Hi Eric,

thanks for answering. I updated the attached figure.
The idea is, we want to show the tree cover difference, but to make
the negative and positive values very contrastive, we would like to
assign the values falling in small range of change (in the figure, it's -1
to 1)
as blank (or gray), in order to make the remaining data constrasting
different.


The most correct way might be to design a new colormap with white color
exactly in the middle, however this is very tedious, especially if I want
to try
different colormaps. so the alternative approach would be to set the values
falling in (-1,1) as being masked, so they will be the same as the axes
background color as you mentioned (in our case it's white). My question is,
how can I put this background color (which shows maksed data) in the
colorbar,
by avoiding design a new colormap?


Then I notice in the colormap methos there is one called "set_bad", I guess
this
is for this purpose, as in the case of "set_over" and "set_under", which
will
influence the colors in the colorbar when you later call the colorbar
method.
But is it not like this?

I invented an example like below:

import numpy as np
import matplotlib as mat
import matplotlib.pyplot as plt

data = np.random.random(10000).reshape(100,100) - 0.5
data_masked = np.ma.masked_inside(data,-0.05,0.05)
cmap = mat.cm.jet
cmap.set_bad('0.5')
fig,ax = plt.subplots(1,1)
lev = [-0.5,-0.4,-0.3,-0.2,-0.1,-0.05,0,0.05,0.1,0.2,0.3,0.4,0.5]
cas = ax.contourf(data_masked,levels=lev,cmap=cmap)
plt.colorbar(cas,ticks=lev)

In this example, how can I make the colors between -0.05 to 0.05 as white,
if I don't want to bother write a new colormap.

Thanks a lot for your time, I hope this case could be useful for others as I
am sure it's very widely used in geographic related sciences.


Cheers,

Chao



On Sat, Mar 1, 2014 at 9:16 PM, Eric Firing [via matplotlib] <
ml-...@n5...> wrote:

> On 2014/03/01 9:57 AM, Chao YUE wrote:
>
> > Dear all,
> >
> > In many cases in geoscience mapping we want to show the some missing
> values
> > as some special color in the colorbar. like attached one.
> >
> > I know there is one method in matplotlib colormap called "set_bad",
> official
> > docs says:
> >
> > Set color to be used for masked values.
> >
> > But I don't know how to make this work when I call the colorbar method.
>
> It is not a matter of calling the colorbar method, but of setting up the
> colormap used on the color-mapped plot for which the colorbar is made.
>
> The one wrinkle to this is that if you are using contourf, the masked
> regions are not filled at all, so they take on the color of the
> background.  To give them the color you assigned to the colormap with
> set_bad, you need to assign that same color to the background, e.g.
>
> ax.set_axis_bgcolor("#bdb76b")
>
> On re-reading your message, however, I think you are asking something
> else, but it is not clear to me from your example exactly what you are
> trying to do.
>
> The colorbar is strictly for a range or sequence of colors, which can
> include triangle regions for the "over" and "under" values; there is no
> place on the colorbar for a "bad" or "missing" value.  Where would you
> put one?  I don't see any such region on the example colorbar you
> attached.
>
> Eric
>
>
>
> > Is there anyone who have the some successful experience?
> >
> > Thanks a lot in advance!
> >
> > Chao
> > --
> >
> ***********************************************************************************
>
> > Chao YUE
> > Laboratoire des Sciences du Climat et de l'Environnement (LSCE-IPSL)
> > UMR 1572 CEA-CNRS-UVSQ
> > Batiment 712 - Pe 119
> > 91191 GIF Sur YVETTE Cedex
> > Tel: (33) 01 69 08 29 02; Fax:01.69.08.77.16
> >
> ************************************************************************************
>
> >
> >
> >
> ------------------------------------------------------------------------------
>
> > Flow-based real-time traffic analytics software. Cisco certified tool.
> > Monitor traffic, SLAs, QoS, Medianet, WAAS etc. with NetFlow Analyzer
> > Customize your own dashboards, set traffic alerts and generate reports.
> > Network behavioral analysis & security monitoring. All-in-one tool.
> >
> http://pubads.g.doubleclick.net/gampad/clk?id=126839071&iu=/4140/ostg.clktrk
> >
> >
> >
> > _______________________________________________
> > Matplotlib-users mailing list
> > [hidden email] <http://user/SendEmail.jtp?type=node&node=42950&i=0>
> > https://lists.sourceforge.net/lists/listinfo/matplotlib-users
> >
>
>
> ------------------------------------------------------------------------------
>
> Flow-based real-time traffic analytics software. Cisco certified tool.
> Monitor traffic, SLAs, QoS, Medianet, WAAS etc. with NetFlow Analyzer
> Customize your own dashboards, set traffic alerts and generate reports.
> Network behavioral analysis & security monitoring. All-in-one tool.
>
> http://pubads.g.doubleclick.net/gampad/clk?id=126839071&iu=/4140/ostg.clktrk
> _______________________________________________
> Matplotlib-users mailing list
> [hidden email] <http://user/SendEmail.jtp?type=node&node=42950&i=1>
> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>
>
> ------------------------------
>  If you reply to this email, your message will be added to the discussion
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>  To start a new topic under matplotlib - users, email
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-- 
***********************************************************************************
Chao YUE
Laboratoire des Sciences du Climat et de l'Environnement (LSCE-IPSL)
UMR 1572 CEA-CNRS-UVSQ
Batiment 712 - Pe 119
91191 GIF Sur YVETTE Cedex
Tel: (33) 01 69 08 29 02; Fax:01.69.08.77.16
************************************************************************************


colorbar_eg.png (74K) <http://matplotlib.1069221.n5.nabble.com/attachment/42951/0/colorbar_eg.png>




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View this message in context: http://matplotlib.1069221.n5.nabble.com/How-can-I-put-a-white-area-in-the-middle-of-colorbar-showing-the-masked-data-tp42948p42951.html
Sent from the matplotlib - users mailing list archive at Nabble.com.

On 2014/03/01 9:57 AM, Chao YUE wrote:
> Dear all,
>
> In many cases in geoscience mapping we want to show the some missing values
> as some special color in the colorbar. like attached one.
>
> I know there is one method in matplotlib colormap called "set_bad", official
> docs says:
>
> Set color to be used for masked values.
>
> But I don't know how to make this work when I call the colorbar method.

It is not a matter of calling the colorbar method, but of setting up the 
colormap used on the color-mapped plot for which the colorbar is made.

The one wrinkle to this is that if you are using contourf, the masked 
regions are not filled at all, so they take on the color of the 
background.  To give them the color you assigned to the colormap with 
set_bad, you need to assign that same color to the background, e.g.

ax.set_axis_bgcolor("#bdb76b")

On re-reading your message, however, I think you are asking something 
else, but it is not clear to me from your example exactly what you are 
trying to do.

The colorbar is strictly for a range or sequence of colors, which can 
include triangle regions for the "over" and "under" values; there is no 
place on the colorbar for a "bad" or "missing" value.  Where would you 
put one?  I don't see any such region on the example colorbar you attached.

Eric



> Is there anyone who have the some successful experience?
>
> Thanks a lot in advance!
>
> Chao
> --
> ***********************************************************************************
> Chao YUE
> Laboratoire des Sciences du Climat et de l'Environnement (LSCE-IPSL)
> UMR 1572 CEA-CNRS-UVSQ
> Batiment 712 - Pe 119
> 91191 GIF Sur YVETTE Cedex
> Tel: (33) 01 69 08 29 02; Fax:01.69.08.77.16
> ************************************************************************************
>
>
> ------------------------------------------------------------------------------
> Flow-based real-time traffic analytics software. Cisco certified tool.
> Monitor traffic, SLAs, QoS, Medianet, WAAS etc. with NetFlow Analyzer
> Customize your own dashboards, set traffic alerts and generate reports.
> Network behavioral analysis & security monitoring. All-in-one tool.
> http://pubads.g.doubleclick.net/gampad/clk?id=126839071&iu=/4140/ostg.clktrk
>
>
>
> _______________________________________________
> Matplotlib-users mailing list
> Mat...@li...
> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>

sorry, the attached file may lack surfix type, here is the correct one.

Cheers,

chao


On Sat, Mar 1, 2014 at 8:57 PM, Chao YUE <cha...@gm...> wrote:

> Dear all,
>
> In many cases in geoscience mapping we want to show the some missing values
> as some special color in the colorbar. like attached one.
>
> I know there is one method in matplotlib colormap called "set_bad",
> official
> docs says:
>
> Set color to be used for masked values.
>
> But I don't know how to make this work when I call the colorbar method.
> Is there anyone who have the some successful experience?
>
> Thanks a lot in advance!
>
> Chao
> --
>
> ***********************************************************************************
> Chao YUE
> Laboratoire des Sciences du Climat et de l'Environnement (LSCE-IPSL)
> UMR 1572 CEA-CNRS-UVSQ
> Batiment 712 - Pe 119
> 91191 GIF Sur YVETTE Cedex
> Tel: (33) 01 69 08 29 02; Fax:01.69.08.77.16
>
> ************************************************************************************
>



-- 
***********************************************************************************
Chao YUE
Laboratoire des Sciences du Climat et de l'Environnement (LSCE-IPSL)
UMR 1572 CEA-CNRS-UVSQ
Batiment 712 - Pe 119
91191 GIF Sur YVETTE Cedex
Tel: (33) 01 69 08 29 02; Fax:01.69.08.77.16
************************************************************************************

Dear all,

In many cases in geoscience mapping we want to show the some missing values
as some special color in the colorbar. like attached one.

I know there is one method in matplotlib colormap called "set_bad", official
docs says:

Set color to be used for masked values.

But I don't know how to make this work when I call the colorbar method.
Is there anyone who have the some successful experience?

Thanks a lot in advance!

Chao
-- 
***********************************************************************************
Chao YUE
Laboratoire des Sciences du Climat et de l'Environnement (LSCE-IPSL)
UMR 1572 CEA-CNRS-UVSQ
Batiment 712 - Pe 119
91191 GIF Sur YVETTE Cedex
Tel: (33) 01 69 08 29 02; Fax:01.69.08.77.16
************************************************************************************

Aarthi,

For me to help further, you will need to provide a sample input file, and the script you are trying to use to read that input file.  Then I can go from there.

-Sterling

On Feb 28, 2014, at 1:38PM, Aarthi Reddy wrote:

> It is not an uppercase problem. The other two titles had combination of upper and lower case. All columns have the exact same number of lines and there are no empty entries.
> 
> On Feb 28, 2014, at 3:31 PM, Sterling Smith <sm...@fu...> wrote:
> 
>> You have an uppercase 'Confidence'.  Are you using pandas or numpy?  For numpy, from Piet's email, you need a lowercase key.  What does 
>> `print df['Confidence'].shape`
>> yield?  Because the error looks like you have an array with no size (zero dimensions), so perhaps you are still not reading in your file correctly.
>> 
>> -Sterling
>> 
>> On Feb 28, 2014, at 1:02PM, AR12 wrote:
>> 
>>> Thanks, this worked for two of the columns. For the third column, I get this error: Sorry to bug you about this. Do you know where I can find the solution to this problem?
>>> 
>>> ---------------------------------------------------------------------------
>>> TypeError                                 Traceback (most recent call last)
>>> <ipython-input-10-ae5186552dfe> in <module>()
>>> ----> 1 plt.hist(df['Confidence'],bins=10)
>>> 
>>> /Library/Python/2.7/site-packages/matplotlib-1.4.x-py2.7-macosx-10.9-intel.egg/matplotlib/pyplot.pyc in hist(x, bins, range, normed, weights, cumulative, bottom, histtype, align, orientation, rwidth, log, color, label, stacked, hold, **kwargs)
>>>   2875                       histtype=histtype, align=align, orientation=orientation,
>>>   2876                       rwidth=rwidth, log=log, color=color, label=label,
>>> -> 2877                       stacked=stacked, **kwargs)
>>>   2878         draw_if_interactive()
>>>   2879     finally:
>>> 
>>> /Library/Python/2.7/site-packages/matplotlib-1.4.x-py2.7-macosx-10.9-intel.egg/matplotlib/axes/_axes.pyc in hist(self, x, bins, range, normed, weights, cumulative, bottom, histtype, align, orientation, rwidth, log, color, label, stacked, **kwargs)
>>>   5477             xmax = -np.inf
>>>   5478             for xi in x:
>>> -> 5479                 if len(xi) > 0:
>>>   5480                     xmin = min(xmin, xi.min())
>>>   5481                     xmax = max(xmax, xi.max())
>>> 
>>> TypeError: len() of unsized object
>>> 
>>> 
>>> On Fri, Feb 28, 2014 at 2:42 PM, Paul Hobson-2 [via matplotlib] <[hidden email]> wrote:
>>> Sounds like you want to use pandas, not numpy.
>>> 
>>> import pandas
>>> import matplotlib.pyplot as plt
>>> df = pandas.read_csv('myfile.txt', sep='\t')
>>> plt.hist(data['A'], bins=30)
>>> 
>>> ...should do it for you. 
>>> 
>>> 
>>> On Fri, Feb 28, 2014 at 11:06 AM, AR12 <[hidden email]> wrote:
>>> Hi,
>>> 
>>> I have a csv file where head -5 looks like this:
>>> 
>>> A  B   C
>>> 100  0.45  0.3
>>> 67  0.25  0.4
>>> 50.6  0.2  0.6
>>> 56.4  0.4  0.3
>>> 
>>> The columns are tab separated. I want to load this CSV file and plot the
>>> histogram of the third or second column. I was able to load the csv file
>>> using this:
>>> data=csv2rec('Downloads/Sample.txt',delimiter='\t',skiprows=0)
>>> The file has 2792 rows including the top header row.
>>> 
>>> When I do
>>>>> data['A'] I get this error:
>>> ---------------------------------------------------------------------------
>>> ValueError                                Traceback (most recent call last)
>>> <ipython-input-19-856828b8eaa3> in <module>()
>>> ----> 1 data['A']
>>> 
>>> /Library/Python/2.7/site-packages/numpy-1.9.0.dev_297f54b-py2.7-macosx-10.9-intel.egg/numpy/core/records.pyc
>>> in __getitem__(self, indx)
>>>    457
>>>    458     def __getitem__(self, indx):
>>> --> 459         obj = ndarray.__getitem__(self, indx)
>>>    460         if (isinstance(obj, ndarray) and obj.dtype.isbuiltin):
>>>    461             return obj.view(ndarray)
>>> 
>>> ValueError: field named A not found
>>> 
>>> First is data['A'] supposed to read the whole A column? Once I read the
>>> column I want to be able to plot it. Can I simply do
>>>>> hist(data['A'],bins=30) or something like that.
>>> 
>>> Many thanks,
>>> AR
>>> 
>>> 
>>> 
>>> 
>>> --
>>> View this message in context: http://matplotlib.1069221.n5.nabble.com/Loding-CSV-file-and-plotting-histogram-of-a-particular-column-tp42938.html
>>> Sent from the matplotlib - users mailing list archive at Nabble.com.
>>> 
>>> ------------------------------------------------------------------------------
>>> Flow-based real-time traffic analytics software. Cisco certified tool.
>>> Monitor traffic, SLAs, QoS, Medianet, WAAS etc. with NetFlow Analyzer
>>> Customize your own dashboards, set traffic alerts and generate reports.
>>> Network behavioral analysis & security monitoring. All-in-one tool.
>>> http://pubads.g.doubleclick.net/gampad/clk?id=126839071&iu=/4140/ostg.clktrk
>>> _______________________________________________
>>> Matplotlib-users mailing list
>>> [hidden email]
>>> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>>> 
>>> 
>>> ------------------------------------------------------------------------------ 
>>> Flow-based real-time traffic analytics software. Cisco certified tool. 
>>> Monitor traffic, SLAs, QoS, Medianet, WAAS etc. with NetFlow Analyzer 
>>> Customize your own dashboards, set traffic alerts and generate reports. 
>>> Network behavioral analysis & security monitoring. All-in-one tool. 
>>> http://pubads.g.doubleclick.net/gampad/clk?id=126839071&iu=/4140/ostg.clktrk
>>> _______________________________________________ 
>>> Matplotlib-users mailing list 
>>> [hidden email] 
>>> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>>> 
>>> 
>>> If you reply to this email, your message will be added to the discussion below:
>>> http://matplotlib.1069221.n5.nabble.com/Loding-CSV-file-and-plotting-histogram-of-a-particular-column-tp42938p42942.html
>>> To unsubscribe from Loding CSV file and plotting histogram of a particular column, click here.
>>> NAML
>>> 
>>> 
>>> 
>>> -- 
>>> Aarthi Reddy
>>> 408-603-1385
>>> 
>>> View this message in context: Re: Loding CSV file and plotting histogram of a particular column
>>> Sent from the matplotlib - users mailing list archive at Nabble.com.
>>> ------------------------------------------------------------------------------
>>> Flow-based real-time traffic analytics software. Cisco certified tool.
>>> Monitor traffic, SLAs, QoS, Medianet, WAAS etc. with NetFlow Analyzer
>>> Customize your own dashboards, set traffic alerts and generate reports.
>>> Network behavioral analysis & security monitoring. All-in-one tool.
>>> http://pubads.g.doubleclick.net/gampad/clk?id=126839071&iu=/4140/ostg.clktrk_______________________________________________
>>> Matplotlib-users mailing list
>>> Mat...@li...
>>> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
> 

You have an uppercase 'Confidence'.  Are you using pandas or numpy?  For numpy, from Piet's email, you need a lowercase key.  What does 
`print df['Confidence'].shape`
yield?  Because the error looks like you have an array with no size (zero dimensions), so perhaps you are still not reading in your file correctly.

-Sterling

On Feb 28, 2014, at 1:02PM, AR12 wrote:

> Thanks, this worked for two of the columns. For the third column, I get this error: Sorry to bug you about this. Do you know where I can find the solution to this problem?
> 
> ---------------------------------------------------------------------------
> TypeError                                 Traceback (most recent call last)
> <ipython-input-10-ae5186552dfe> in <module>()
> ----> 1 plt.hist(df['Confidence'],bins=10)
> 
> /Library/Python/2.7/site-packages/matplotlib-1.4.x-py2.7-macosx-10.9-intel.egg/matplotlib/pyplot.pyc in hist(x, bins, range, normed, weights, cumulative, bottom, histtype, align, orientation, rwidth, log, color, label, stacked, hold, **kwargs)
>    2875                       histtype=histtype, align=align, orientation=orientation,
>    2876                       rwidth=rwidth, log=log, color=color, label=label,
> -> 2877                       stacked=stacked, **kwargs)
>    2878         draw_if_interactive()
>    2879     finally:
> 
> /Library/Python/2.7/site-packages/matplotlib-1.4.x-py2.7-macosx-10.9-intel.egg/matplotlib/axes/_axes.pyc in hist(self, x, bins, range, normed, weights, cumulative, bottom, histtype, align, orientation, rwidth, log, color, label, stacked, **kwargs)
>    5477             xmax = -np.inf
>    5478             for xi in x:
> -> 5479                 if len(xi) > 0:
>    5480                     xmin = min(xmin, xi.min())
>    5481                     xmax = max(xmax, xi.max())
> 
> TypeError: len() of unsized object
> 
> 
> On Fri, Feb 28, 2014 at 2:42 PM, Paul Hobson-2 [via matplotlib] <[hidden email]> wrote:
> Sounds like you want to use pandas, not numpy.
> 
> import pandas
> import matplotlib.pyplot as plt
> df = pandas.read_csv('myfile.txt', sep='\t')
> plt.hist(data['A'], bins=30)
> 
> ...should do it for you. 
> 
> 
> On Fri, Feb 28, 2014 at 11:06 AM, AR12 <[hidden email]> wrote:
> Hi,
> 
> I have a csv file where head -5 looks like this:
> 
> A  B   C
> 100  0.45  0.3
> 67  0.25  0.4
> 50.6  0.2  0.6
> 56.4  0.4  0.3
> 
> The columns are tab separated. I want to load this CSV file and plot the
> histogram of the third or second column. I was able to load the csv file
> using this:
> data=csv2rec('Downloads/Sample.txt',delimiter='\t',skiprows=0)
> The file has 2792 rows including the top header row.
> 
> When I do
> >> data['A'] I get this error:
> ---------------------------------------------------------------------------
> ValueError                                Traceback (most recent call last)
> <ipython-input-19-856828b8eaa3> in <module>()
> ----> 1 data['A']
> 
> /Library/Python/2.7/site-packages/numpy-1.9.0.dev_297f54b-py2.7-macosx-10.9-intel.egg/numpy/core/records.pyc
> in __getitem__(self, indx)
>     457
>     458     def __getitem__(self, indx):
> --> 459         obj = ndarray.__getitem__(self, indx)
>     460         if (isinstance(obj, ndarray) and obj.dtype.isbuiltin):
>     461             return obj.view(ndarray)
> 
> ValueError: field named A not found
> 
> First is data['A'] supposed to read the whole A column? Once I read the
> column I want to be able to plot it. Can I simply do
> >> hist(data['A'],bins=30) or something like that.
> 
> Many thanks,
> AR
> 
> 
> 
> 
> --
> View this message in context: http://matplotlib.1069221.n5.nabble.com/Loding-CSV-file-and-plotting-histogram-of-a-particular-column-tp42938.html
> Sent from the matplotlib - users mailing list archive at Nabble.com.
> 
> ------------------------------------------------------------------------------
> Flow-based real-time traffic analytics software. Cisco certified tool.
> Monitor traffic, SLAs, QoS, Medianet, WAAS etc. with NetFlow Analyzer
> Customize your own dashboards, set traffic alerts and generate reports.
> Network behavioral analysis & security monitoring. All-in-one tool.
> http://pubads.g.doubleclick.net/gampad/clk?id=126839071&iu=/4140/ostg.clktrk
> _______________________________________________
> Matplotlib-users mailing list
> [hidden email]
> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
> 
> 
> ------------------------------------------------------------------------------ 
> Flow-based real-time traffic analytics software. Cisco certified tool. 
> Monitor traffic, SLAs, QoS, Medianet, WAAS etc. with NetFlow Analyzer 
> Customize your own dashboards, set traffic alerts and generate reports. 
> Network behavioral analysis & security monitoring. All-in-one tool. 
> http://pubads.g.doubleclick.net/gampad/clk?id=126839071&iu=/4140/ostg.clktrk
> _______________________________________________ 
> Matplotlib-users mailing list 
> [hidden email] 
> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
> 
> 
> If you reply to this email, your message will be added to the discussion below:
> http://matplotlib.1069221.n5.nabble.com/Loding-CSV-file-and-plotting-histogram-of-a-particular-column-tp42938p42942.html
> To unsubscribe from Loding CSV file and plotting histogram of a particular column, click here.
> NAML
> 
> 
> 
> -- 
> Aarthi Reddy
> 408-603-1385
> 
> View this message in context: Re: Loding CSV file and plotting histogram of a particular column
> Sent from the matplotlib - users mailing list archive at Nabble.com.
> ------------------------------------------------------------------------------
> Flow-based real-time traffic analytics software. Cisco certified tool.
> Monitor traffic, SLAs, QoS, Medianet, WAAS etc. with NetFlow Analyzer
> Customize your own dashboards, set traffic alerts and generate reports.
> Network behavioral analysis & security monitoring. All-in-one tool.
> http://pubads.g.doubleclick.net/gampad/clk?id=126839071&iu=/4140/ostg.clktrk_______________________________________________
> Matplotlib-users mailing list
> Mat...@li...
> https://lists.sourceforge.net/lists/listinfo/matplotlib-users

Thanks, this worked for two of the columns. For the third column, I get
this error: Sorry to bug you about this. Do you know where I can find the
solution to this problem?

---------------------------------------------------------------------------

TypeError                                 Traceback (most recent call last)

<ipython-input-10-ae5186552dfe> in <module>()

----> 1 plt.hist(df['Confidence'],bins=10)


/Library/Python/2.7/site-packages/matplotlib-1.4.x-py2.7-macosx-10.9-intel.egg/matplotlib/pyplot.pycin
hist(x, bins, range, normed, weights, cumulative, bottom, histtype, align,
orientation, rwidth, log, color, label, stacked, hold, **kwargs)

   2875                       histtype=histtype, align=align, orientation=
orientation,

   2876                       rwidth=rwidth, log=log, color=color, label=
label,

-> 2877                       stacked=stacked, **kwargs)

   2878         draw_if_interactive()

   2879     finally:


/Library/Python/2.7/site-packages/matplotlib-1.4.x-py2.7-macosx-10.9-intel.egg/matplotlib/axes/_axes.pycin
hist(self, x, bins, range, normed, weights, cumulative, bottom, histtype,
align, orientation, rwidth, log, color, label, stacked, **kwargs)

   5477             xmax = -np.inf

   5478             for xi in x:

-> 5479                 if len(xi) > 0:

   5480                     xmin = min(xmin, xi.min())

   5481                     xmax = max(xmax, xi.max())


TypeError: len() of unsized object


On Fri, Feb 28, 2014 at 2:42 PM, Paul Hobson-2 [via matplotlib] <
ml-...@n5...> wrote:

> Sounds like you want to use pandas, not numpy.
>
> import pandas
> import matplotlib.pyplot as plt
> df = pandas.read_csv('myfile.txt', sep='\t')
> plt.hist(data['A'], bins=30)
>
> ...should do it for you.
>
>
>  On Fri, Feb 28, 2014 at 11:06 AM, AR12 <[hidden email]<http://user/SendEmail.jtp?type=node&node=42942&i=0>
> > wrote:
>
>> Hi,
>>
>> I have a csv file where head -5 looks like this:
>>
>> A  B   C
>> 100  0.45  0.3
>> 67  0.25  0.4
>> 50.6  0.2  0.6
>> 56.4  0.4  0.3
>>
>> The columns are tab separated. I want to load this CSV file and plot the
>> histogram of the third or second column. I was able to load the csv file
>> using this:
>> data=csv2rec('Downloads/Sample.txt',delimiter='\t',skiprows=0)
>> The file has 2792 rows including the top header row.
>>
>> When I do
>> >> data['A'] I get this error:
>>
>> ---------------------------------------------------------------------------
>> ValueError                                Traceback (most recent call
>> last)
>> <ipython-input-19-856828b8eaa3> in <module>()
>> ----> 1 data['A']
>>
>>
>> /Library/Python/2.7/site-packages/numpy-1.9.0.dev_297f54b-py2.7-macosx-10.9-intel.egg/numpy/core/records.pyc
>> in __getitem__(self, indx)
>>     457
>>     458     def __getitem__(self, indx):
>> --> 459         obj = ndarray.__getitem__(self, indx)
>>     460         if (isinstance(obj, ndarray) and obj.dtype.isbuiltin):
>>     461             return obj.view(ndarray)
>>
>> ValueError: field named A not found
>>
>> First is data['A'] supposed to read the whole A column? Once I read the
>> column I want to be able to plot it. Can I simply do
>> >> hist(data['A'],bins=30) or something like that.
>>
>> Many thanks,
>> AR
>>
>>
>>
>>
>> --
>> View this message in context:
>> http://matplotlib.1069221.n5.nabble.com/Loding-CSV-file-and-plotting-histogram-of-a-particular-column-tp42938.html
>> Sent from the matplotlib - users mailing list archive at Nabble.com.
>>
>>
>> ------------------------------------------------------------------------------
>> Flow-based real-time traffic analytics software. Cisco certified tool.
>> Monitor traffic, SLAs, QoS, Medianet, WAAS etc. with NetFlow Analyzer
>> Customize your own dashboards, set traffic alerts and generate reports.
>> Network behavioral analysis & security monitoring. All-in-one tool.
>>
>> http://pubads.g.doubleclick.net/gampad/clk?id=126839071&iu=/4140/ostg.clktrk
>> _______________________________________________
>> Matplotlib-users mailing list
>> [hidden email] <http://user/SendEmail.jtp?type=node&node=42942&i=1>
>> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>>
>
>
> ------------------------------------------------------------------------------
>
> Flow-based real-time traffic analytics software. Cisco certified tool.
> Monitor traffic, SLAs, QoS, Medianet, WAAS etc. with NetFlow Analyzer
> Customize your own dashboards, set traffic alerts and generate reports.
> Network behavioral analysis & security monitoring. All-in-one tool.
>
> http://pubads.g.doubleclick.net/gampad/clk?id=126839071&iu=/4140/ostg.clktrk
> _______________________________________________
> Matplotlib-users mailing list
> [hidden email] <http://user/SendEmail.jtp?type=node&node=42942&i=2>
> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>
>
> ------------------------------
>  If you reply to this email, your message will be added to the discussion
> below:
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-- 
Aarthi Reddy
408-603-1385




--
View this message in context: http://matplotlib.1069221.n5.nabble.com/Loding-CSV-file-and-plotting-histogram-of-a-particular-column-tp42938p42944.html
Sent from the matplotlib - users mailing list archive at Nabble.com.

AR12 wrote:

 > Hi,
 > 
 > I have a csv file where head -5 looks like this:
 > 
 > A  B   C
 > 100  0.45  0.3
 > 67  0.25  0.4
 > 50.6  0.2  0.6
 > 56.4  0.4  0.3
 > 
 > The columns are tab separated. I want to load this CSV file and plot the
 > histogram of the third or second column. I was able to load the csv file
 > using this:
 > data=csv2rec('Downloads/Sample.txt',delimiter='\t',skiprows=0)
 > The file has 2792 rows including the top header row.
 > 
 > When I do
 > >> data['A'] I get this error:
 > ---------------------------------------------------------------------------
 > ValueError                                Traceback (most recent call last)
 > <ipython-input-19-856828b8eaa3> in <module>()
 > ----> 1 data['A']

numpy.csv2rec lowercases the column names.
"If *names* is *None*, a header row is required to automatically
assign the recarray names.  The headers will be lower cased,
spaces will be converted to underscores, and illegal attribute
name characters removed.  If *names* is not *None*, it is a
sequence of names to use for the column names.  In this case, it
is assumed there is no header row."

So data['a'] should do it.
-- 
Piet van Oostrum <pi...@va...>
WWW: http://pietvanoostrum.com/
PGP key: [8DAE142BE17999C4]

Sounds like you want to use pandas, not numpy.

import pandas
import matplotlib.pyplot as plt
df = pandas.read_csv('myfile.txt', sep='\t')
plt.hist(data['A'], bins=30)

...should do it for you.


On Fri, Feb 28, 2014 at 11:06 AM, AR12 <aar...@gm...> wrote:

> Hi,
>
> I have a csv file where head -5 looks like this:
>
> A  B   C
> 100  0.45  0.3
> 67  0.25  0.4
> 50.6  0.2  0.6
> 56.4  0.4  0.3
>
> The columns are tab separated. I want to load this CSV file and plot the
> histogram of the third or second column. I was able to load the csv file
> using this:
> data=csv2rec('Downloads/Sample.txt',delimiter='\t',skiprows=0)
> The file has 2792 rows including the top header row.
>
> When I do
> >> data['A'] I get this error:
> ---------------------------------------------------------------------------
> ValueError                                Traceback (most recent call last)
> <ipython-input-19-856828b8eaa3> in <module>()
> ----> 1 data['A']
>
>
> /Library/Python/2.7/site-packages/numpy-1.9.0.dev_297f54b-py2.7-macosx-10.9-intel.egg/numpy/core/records.pyc
> in __getitem__(self, indx)
>     457
>     458     def __getitem__(self, indx):
> --> 459         obj = ndarray.__getitem__(self, indx)
>     460         if (isinstance(obj, ndarray) and obj.dtype.isbuiltin):
>     461             return obj.view(ndarray)
>
> ValueError: field named A not found
>
> First is data['A'] supposed to read the whole A column? Once I read the
> column I want to be able to plot it. Can I simply do
> >> hist(data['A'],bins=30) or something like that.
>
> Many thanks,
> AR
>
>
>
>
> --
> View this message in context:
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On 02/27/2014 06:58 PM, Jon Roadley-Battin wrote:
> Good evening,
>
> I am at present migrating an application of mine from py27+pygtk (with 
> mpl) to py33+pygobject (gtk3)
>
> Unfortunately I am unable to use
>
> from  matplotlib.backends.backend_gtk3agg  import  FigureCanvasGTK3Agg  as  FigureCanvas
> from  matplotlib.backends.backend_gtk3  import  NavigationToolbar2GTK3  as  NavigationToolbar
>
> Which is is on the examples ( 
> http://matplotlib.org/examples/user_interfaces/embedding_in_gtk3_panzoom.html 
> ) but is also the logical translation from what I presently have.
> This falls fowl of the cairo issue
>
> What I am having to use is backend_gtk3cairo. However this is being 
> triggered
>
>  raise ValueError("The Cairo backend can not draw paths longer than 
> 18980 points.")
>
> I am generally plotting 7 x-y plots with upto 30,000 points.
> Now for now I have commented this out from my local install, is there 
> a better/preferred/recommended alternative?

This was put in there because cairo had (at least at the time) a hard 
coded limit on path size, and getting a Python exception was IMHO 
preferable to segfaulting and having the process go away.  Are you 
saying that when you comment it out, it's currently working?  It may be 
that cairo has fixed this limit in the intervening years. Can you 
provide a simple, standalone example that reproduces the error?

> I have read about cairocffi but this doesn't 
> seem conveniently possible at this moment in time (especially for 
> windows)

I'm not sure if the Python wrappers will matter, since this issue is 
actually in the underlying Cairo library.

>
> Equally I have seen mpl-devel mailing list entries from 4years ago 
> stating that this check was to be removed (a cairo 1.4.10 issue)

Are you referring to this thread?

http://matplotlib.1069221.n5.nabble.com/Path-length-in-the-cairo-backend-td36582.html

The conclusion there (if you scroll down) was that the check is still 
needed as of Cairo 1.8.

Mike

>
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>
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http://www.droettboom.com

Sorry, it seems that I didn't have dvipng installed correctly!


On Fri, Feb 28, 2014 at 2:53 PM, Adam Hughes <hug...@gm...> wrote:

> Hi,
>
> In an IPython notebook, I've changed several setting in both the
> notebook's style and the plotting style.  I noticed that when I change the
> usetex option in the rcparams:
>
> *rcParams['text.usetex'] = True *
>
> Then I add an integral sign as text to a plot (either title or axis label)
>
> *plt.title($\int_0^\infty$)*
>
> The integral symbol is not rendered.  Changing usetex to false results in
> properly rendering.
>
> Can anyone reproduce this?
>
>

Hi,

In an IPython notebook, I've changed several setting in both the notebook's
style and the plotting style.  I noticed that when I change the usetex
option in the rcparams:

*rcParams['text.usetex'] = True *

Then I add an integral sign as text to a plot (either title or axis label)

*plt.title($\int_0^\infty$)*

The integral symbol is not rendered.  Changing usetex to false results in
properly rendering.

Can anyone reproduce this?

Hi,

I have a csv file where head -5 looks like this:

A  B   C
100  0.45  0.3
67  0.25  0.4
50.6  0.2  0.6
56.4  0.4  0.3

The columns are tab separated. I want to load this CSV file and plot the
histogram of the third or second column. I was able to load the csv file
using this:
data=csv2rec('Downloads/Sample.txt',delimiter='\t',skiprows=0)
The file has 2792 rows including the top header row.

When I do
>> data['A'] I get this error:
---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-19-856828b8eaa3> in <module>()
----> 1 data['A']

/Library/Python/2.7/site-packages/numpy-1.9.0.dev_297f54b-py2.7-macosx-10.9-intel.egg/numpy/core/records.pyc
in __getitem__(self, indx)
    457 
    458     def __getitem__(self, indx):
--> 459         obj = ndarray.__getitem__(self, indx)
    460         if (isinstance(obj, ndarray) and obj.dtype.isbuiltin):
    461             return obj.view(ndarray)

ValueError: field named A not found

First is data['A'] supposed to read the whole A column? Once I read the
column I want to be able to plot it. Can I simply do 
>> hist(data['A'],bins=30) or something like that.

Many thanks,
AR




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View this message in context: http://matplotlib.1069221.n5.nabble.com/Loding-CSV-file-and-plotting-histogram-of-a-particular-column-tp42938.html
Sent from the matplotlib - users mailing list archive at Nabble.com.

Good evening,

I am at present migrating an application of mine from py27+pygtk (with mpl)
to py33+pygobject (gtk3)

Unfortunately I am unable to use

from matplotlib.backends.backend_gtk3agg import FigureCanvasGTK3Agg as
FigureCanvasfrom matplotlib.backends.backend_gtk3 import
NavigationToolbar2GTK3 as NavigationToolbar


Which is is on the examples (
http://matplotlib.org/examples/user_interfaces/embedding_in_gtk3_panzoom.html)
but is also the logical translation from what I presently have.
This falls fowl of the cairo issue

What I am having to use is backend_gtk3cairo. However this is being
triggered

 raise ValueError("The Cairo backend can not draw paths longer than 18980
points.")

I am generally plotting 7 x-y plots with upto 30,000 points.
Now for now I have commented this out from my local install, is there a
better/preferred/recommended alternative?
I have read about cairocffi but this doesn't seem conveniently possible at
this moment in time (especially for windows)

Equally I have seen mpl-devel mailing list entries from 4years ago stating
that this check was to be removed (a cairo 1.4.10 issue)

JonRB

I'm trying to do a twiny setup on one of the Axes generated from a
make_axes_locatable().append_axes() call. The new axis generated from
twiny() seems to span the entire window though. Here's the code:

from matplotlib.pyplot import *
import numpy as np
from mpl_toolkits.axes_grid1 import make_axes_locatable

ax_c = subplot(111)
ax_c.plot(np.linspace(0,10))

divider = make_axes_locatable(ax_c)
ax_t = divider.append_axes("top", size=1.2, pad=0.1, sharex=ax_c)
ax_r = divider.append_axes("right", size=1.2, pad=0.1, sharey=ax_c)
ax_r.plot(np.linspace(0,50))
ax_t.plot(np.linspace(0,25))

ax_ty = ax_r.twiny()
ax_ty.plot(np.linspace(-50,0))

show()


If you get the idea of what I'm trying to do, other suggestions involving
AxesGrid, subplots, or otherwise are welcome. AxesGrid seems to require
that I have all four plots in a 2x2 grid (in the above code there are only
3), and using subplots would seemingly require the rightmost plot to span
the height of the other two. There's this:
http://matplotlib.org/examples/pylab_examples/scatter_hist.html but I don't
want to hard-code the dimensions, as the center subplot should change
dimensions as I put in new data...

Does anyone know the preferred method for stopping FuncAnimation? I am using it to record data from a oscilloscope and woud like to be able to pause and restart the data on demand. Is there any way I can send a button click event to it?

Thanks, Derek

Hi,

when I try to change the ylim and xlim directly from the displayed canvas i
get this error(when  I change them in the code I have no problems):

Traceback (most recent call last):
  File "C:\Anaconda\lib\site-packages\matplotlib\backends\backend_qt4.py",
line
594, in edit_parameters
    figureoptions.figure_edit(axes, self)
  File
"C:\Anaconda\lib\site-packages\matplotlib\backends\qt4_editor\figureoptio
ns.py", line 134, in figure_edit
    icon=get_icon('qt4_editor_options.svg'), apply=apply_callback)
  File
"C:\Anaconda\lib\site-packages\matplotlib\backends\qt4_editor\formlayout.py",
line 544, in fedit
    dialog = FormDialog(data, title, comment, icon, parent, apply)
  File
"C:\Anaconda\lib\site-packages\matplotlib\backends\qt4_editor\formlayout.py",
line 461, in __init__
    self.formwidget.setup()
  File
"C:\Anaconda\lib\site-packages\matplotlib\backends\qt4_editor\formlayout.py",
line 433, in setup
    widget.setup()
  File
"C:\Anaconda\lib\site-packages\matplotlib\backends\qt4_editor\formlayout.py",
line 408, in setup
    widget.setup()
  File
"C:\Anaconda\lib\site-packages\matplotlib\backends\qt4_editor\formlayout.py",
line 302, in setup
    field = ColorLayout(QColor(value), self)
TypeError: QVariant must be holding a QColor

my code is:
fig = plt.figure()
figf = plt.figure()

for el in sequence:
        #some operations
        ax = fig.add_subplot(111)

        img = ax.plot(xflo, yflo, label=etich, marker = '.')
        ax.set_yscale('log')
        ax.set_xscale('log')
        ax.legend(bbox_to_anchor=(1.05, 1), loc=4, borderaxespad=0.)
        fig.canvas.draw()
        ax1 = figf.add_subplot(111)

        img1 = ax1.plot(logx, logy, label=etich)#, marker = style)
        ax1.legend(bbox_to_anchor=(1.05, 1), loc=4, borderaxespad=0.)

        figf.canvas.draw()

thanks

Gabriele

Hi
It has been reported in
http://matplotlib.1069221.n5.nabble.com/How-to-properly-use-path-Path-contains-point-td40718.htmlbut
I do not see anything has happened after this.
Following code illustrates the problem, when polygon defined in one
direction, I can check if point is inside it, if other direction, I can
not.

from matplotlib.patches import Polygon

poly1=Polygon([[0.,0.],[1.,0.],[1.,1.],[0.,1.]],facecolor='none')
print(poly1.contains_point([0.5,0.5]))

poly2=Polygon([[0.,0.],[0.,1.],[1.,1.],[1.,0.]],facecolor='none')
print(poly2.contains_point([0.5,0.5]))
print(poly2.contains_point([-0.5,-0.5]))

I do not see an obvious reason why polygons should be defined in one
direction only.

I have tried the code with several versions of matplotlib, newest is 1.3.1
with numpy 1.8 and python 3.2.3 and all newer versions do not work as I
would accept them. Only the oldest version, python2.6.6 with matplotlib
0.99.1.1 gives me correct answer.

I have digged in the source code and ended up in file _path.cpp where the
function point_in_path_impl seems to do the actual job, but understanding
it completely seems to take more time than I have at the moment.

Any feedback appreciated.

Andres

You're not adding your subplot to an existing figure, so a new one is
created.

put "fig = plt.figure(...)" at the top of your script and replace "axii =
plt.subplot(numalp, numobs, axisNum)" with "axii = fig.add_subplot(numalp,
numobs, axisNum)"


On Sat, Feb 22, 2014 at 5:28 PM, Gabriele Brambilla <
gb....@gm...> wrote:

> Hi,
> I'm trying to follow this example to make a grid of subplot:
>
> http://matplotlib.org/examples/pylab_examples/line_styles.html
>
> but my code plot the two rows in two different figures (i attach them but
> I don't know if they are useful). Does anyone understand why?
>
> this is an extract of my code:
>
> alphas = [45, 75]
> numalp = len(alphas)
>
> angles = np.linspace(pi/12, pi/2, num=10)
> numobs = len(angles)
>
> axisNum = 0
>
> for a in alphas:
>
>           #[some operations]
>
>           for obsangl in angles:
>
>                        #[some operations]
>
>                        axisNum += 1
>                        axii = plt.subplot(numalp, numobs, axisNum)
>                        plt.errorbar(g, Pgamma, yerr = ePgamma, color =
> 'green', fmt = '.')
>                        axii1 = axii.twinx()
>                        plt.plot(g, lightcurva, 'b-')
>                        axii.set_yticklabels([])
>                        axii.set_xticklabels([])
>                        axii1.set_yticklabels([])
>                        axii1.set_xticklabels([])
>
>
>
>
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Hi Fadzil,

Ah sorry, I glossed over that part of your question. There are actually two
solutions to this, one would be to actually find the indices where the
latitudes and longitudes are within your desired bounds using
numpy.where(). However I generally prefer to use numpy's built-in fancy
indexing for this type of problem. For example:

# lat and lon are extracted from the netcdf file, assumed to be 1D
# Determine which latitudes are between 20S and 10N
latidx = (lat >= -20) & (lat <= 10)

# Determine which longitudes are between 130E and 170E.
# The numbers here may differ depending on the longitude convention in your
data.
lonidx = (lon >= 130) & (lon <= 170)

# Now we will actually subset the data. We need to subset lat too to make
sure weights are consistent.
sst = sstv[:]
sst = sst[:, latidx][..., lonidx]
lat = lat[latidx]

Yes, the indexing does get a little tricky but it should work if you do it
this way, then follow the same procedure outlined in the previous email.

Thanks,
Alex

On Sun, Feb 23, 2014 at 6:02 PM, Fadzil Mnor <fad...@gm...> wrote:

> Thanks Alex for the reply.
> So, that script calculates the global SST. What if when we want to
> calculate for only in specific box? For example, SST over this area only:
>
> ----------------------------------- 10 N
> |                                             |
> |                                             |
> |                                             |
> |                   SST                  |
> |                                             |
> |                                             |
> ----------------------------------- 20 S
> 130 E                                 170E
>
> Thanks.
>
> Fadzil
>



-- 
Alex Goodman
Graduate Research Assistant
Department of Atmospheric Science
Colorado State University