matplotlib-users Mailing List for matplotlib

I loaded matplotlib following the instructions in
http://matplotlib.sourceforge.net/users/shell.html, including setting up the
matplotlibrc file.  But the xlabel command hangs.

In detail:

bash-3.2$ python -i
Python 2.6.1 (r261:67517, Dec  4 2008, 16:51:00) [MSC v.1500 32 bit (Intel)]
on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import pylab
>>> from pylab import *
>>> plot([1,2,1])
--------------------------------------displays
plot------------------------------------
[<matplotlib.lines.Line2D object at 0x019DE430>]
>>> xlabel('hi mom')
--------------------------------------hangs
forever-----------------------------------

I am running Python 2.6.1 in an Emacs shell buffer; the Python is running on
Cygwin on Windows XP.  I am not using ipython.

What am I doing wrong?

Thanks,

            -s

Greetings, MPL Users.

I have been experimenting with Axes3D with the hopes that I could create
some 3d lines and then project some contours on different planes in the 3D
axes object, much like the contour3d_demo3.py example (but with lines
instead of the 3d wireframe.)  The catch, however, is creating the contour
objects using tricontour instead of a regular contour.  Being that I
typically use irregular grids for my research, the triangulate module has
been a tremendous feature, but it doesn't seem to work with Axes3D objects.

For example, this quick script:
import matplotlib.pyplot as plt
#import matplotlib.tri as tri
import numpy as np
from numpy.random import uniform, seed
from mpl_toolkits.mplot3d import Axes3D

seed(0)
npts = 200
ngridx = 100
ngridy = 200
x = uniform(-2,2,npts)
y = uniform(-2,2,npts)
z = x*np.exp(-x**2-y**2)

# tricontour.
fig = plt.figure()
ax = Axes3D(fig)
ax.tricontour(x, y, z, 15, zdir=x, offset=-2)

plt.show()

creates a huge traceback, listed below.
Is it possible to combine tricontour with Axes3D?  It would appear that they
are just incompatible, but perhaps there is a way to force it to work?
Thanks for your help.

tricont3d.py in <module>()
     20 ax.tricontour(x, y, z, 15, zdir=x, offset=-2)
     21
---> 22 plt.show()
     23
     24

python2.6/site-packages/matplotlib/backends/backend_qt4.pyc in show()
     69     figManager =  Gcf.get_active()
     70     if figManager != None:
---> 71         figManager.canvas.draw()
     72
     73     if _create_qApp.qAppCreatedHere:

python2.6/site-packages/matplotlib/backends/backend_qt4agg.pyc in draw(self)
    128         if DEBUG: print "FigureCanvasQtAgg.draw", self
    129         self.replot = True
--> 130         FigureCanvasAgg.draw(self)
    131         self.update()
    132
site-packages/matplotlib/backends/backend_agg.pyc in draw(self)
    392
    393         self.renderer = self.get_renderer()
--> 394         self.figure.draw(self.renderer)
    395
    396     def get_renderer(self):

python2.6/site-packages/matplotlib/artist.pyc in draw_wrapper(artist,
renderer, *args, **kwargs)
     53     def draw_wrapper(artist, renderer, *args, **kwargs):
     54         before(artist, renderer)
---> 55         draw(artist, renderer, *args, **kwargs)
     56         after(artist, renderer)
     57

python2.6/site-packages/matplotlib/figure.pyc in draw(self, renderer)
    796         dsu.sort(key=itemgetter(0))
    797         for zorder, func, args in dsu:
--> 798             func(*args)
    799
    800         renderer.close_group('figure')

python2.6/site-packages/mpl_toolkits/mplot3d/axes3d.pyc in draw(self,
renderer)
    152         # Calculate projection of collections and zorder them

    153         zlist = [(col.do_3d_projection(renderer), col) \
--> 154                  for col in self.collections]
    155         zlist.sort()
    156         zlist.reverse()

AttributeError: 'LineCollection' object has no attribute 'do_3d_projection'
WARNING: Failure executing file: <tricont3d.py>

On Mon, Jul 19, 2010 at 9:55 AM, Bala subramanian <bal...@gm...
> wrote:

> Friends,
>
> Attached a script test.py and 2 data files using with which i am trying to
> make a bar plot. The output is coming nice, but the x-ticks are placed at
> the left edge of the first bar. I want to make the xticks at the center
> between the two bars to have a better visualization. I dnt get which
> arguement i should use to get the xticks at the center of the two bars as in
> the following example
>
>
> http://matplotlib.sourceforge.net/examples/pylab_examples/barchart_demo.html
>
> Thanks,
> Bala
>

Bala,

There are two issues with your current code.  First, you are setting the x
limits of your plot to [1, 40], which causes the last red bar to be clipped
out.  You should set it to [1, 40 + width].  Second, the set_xticks() needs
to be shifted by width.  However, doing so will change the values. So, it
seems that if you change

ax.set_xticks(ind)

to

plt.xticks(ind + width, ind)

The ticks will be placed at the positions 'ind + width', but with the values
'ind'.  I hope this helps.

Ben Root

My MPL version is '0.98.5.2' and my OS is Ubuntu 9.04. I tried again but it
is still giving me that error. Weird.



João Luís Silva-2 wrote:
> 
> On 07/19/2010 03:11 PM, Clear wrote:
>>
>> plt.plot(x,np.sin(x),"-s",markevery=N/50)
>>
>> I have tried your option but a message is returned to me which says that
>> markevery is an unknown property. I have included exactly the code you
>> propose. May I guess why I am getting such error?
>>
>> Clear
>>
>>
> 
> Are you sure you ran the example as I sent it? markevery should be 
> available since matplotlib version 0.98.5.2, released at the end of 
> 2008. Which mpl version and operating system are you using?
> 
> JLS
> 
> 
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On Wed, Jul 14, 2010 at 4:54 AM, Robert Hancock <re...@ag...> wrote:

> Hi
>
> I am trying to use autofmt_xdate() on graphs with more than 1 y-axis. But
> it
> seems that even calling twinx() causes errors. On python 2.5 matplotlib
> 0.98
> a call to twinx() seems to switch off the functioning of autofmt_xdate()
> (and the labels are horizontal and mashed up). On python 2.6 and matplotlib
> 1.0.0 it causes a ValueError.
>
> The following script illustrates the issue (in real life I obviously want
> to
> do things with ax2, but it seems that even creating it causes problems). Is
> there a simple working example of rotated data formats and twinx()?
>
> robert
>
> import datetime
> import matplotlib
> matplotlib.use('Agg')
> import matplotlib.pyplot as plt
>
> date=[datetime.datetime(2010,1,1), datetime.datetime(2010,12,1)]
> data=[1,2]
>
> fig = plt.figure()
> ax = fig.add_subplot(111)
> # uncommenting the following line will lead to the problems
> # ax2=ax.twinx()
> ax.plot(date, data)
>
> fig.autofmt_xdate(rotation=90)
>
> fig.savefig("test3.png", dpi=400)
>
>
>
For further information, here is the Value Error on matplotlib 1.0
(replacing the savefig with a show):

Traceback (most recent call last):
  File
"/home/bvr/Programs/matplotlib/matplotlib/lib/matplotlib/backends/backend_gtk.py",
line 389, in expose_event
    self._render_figure(self._pixmap, w, h)
  File
"/home/bvr/Programs/matplotlib/matplotlib/lib/matplotlib/backends/backend_gtkagg.py",
line 75, in _render_figure
    FigureCanvasAgg.draw(self)
  File
"/home/bvr/Programs/matplotlib/matplotlib/lib/matplotlib/backends/backend_agg.py",
line 394, in draw
    self.figure.draw(self.renderer)
  File "/home/bvr/Programs/matplotlib/matplotlib/lib/matplotlib/artist.py",
line 55, in draw_wrapper
    draw(artist, renderer, *args, **kwargs)
  File "/home/bvr/Programs/matplotlib/matplotlib/lib/matplotlib/figure.py",
line 798, in draw
    func(*args)
  File "/home/bvr/Programs/matplotlib/matplotlib/lib/matplotlib/artist.py",
line 55, in draw_wrapper
    draw(artist, renderer, *args, **kwargs)
  File "/home/bvr/Programs/matplotlib/matplotlib/lib/matplotlib/axes.py",
line 1934, in draw
    a.draw(renderer)
  File "/home/bvr/Programs/matplotlib/matplotlib/lib/matplotlib/artist.py",
line 55, in draw_wrapper
    draw(artist, renderer, *args, **kwargs)
  File "/home/bvr/Programs/matplotlib/matplotlib/lib/matplotlib/axis.py",
line 971, in draw
    tick_tups = [ t for t in self.iter_ticks()]
  File "/home/bvr/Programs/matplotlib/matplotlib/lib/matplotlib/axis.py",
line 904, in iter_ticks
    majorLocs = self.major.locator()
  File "/home/bvr/Programs/matplotlib/matplotlib/lib/matplotlib/dates.py",
line 743, in __call__
    self.refresh()
  File "/home/bvr/Programs/matplotlib/matplotlib/lib/matplotlib/dates.py",
line 752, in refresh
    dmin, dmax = self.viewlim_to_dt()
  File "/home/bvr/Programs/matplotlib/matplotlib/lib/matplotlib/dates.py",
line 524, in viewlim_to_dt
    return num2date(vmin, self.tz), num2date(vmax, self.tz)
  File "/home/bvr/Programs/matplotlib/matplotlib/lib/matplotlib/dates.py",
line 289, in num2date
    if not cbook.iterable(x): return _from_ordinalf(x, tz)
  File "/home/bvr/Programs/matplotlib/matplotlib/lib/matplotlib/dates.py",
line 203, in _from_ordinalf
    dt = datetime.datetime.fromordinal(ix)
ValueError: ordinal must be >= 1

Ben Root

Friends,

Attached a script test.py and 2 data files using with which i am trying to
make a bar plot. The output is coming nice, but the x-ticks are placed at
the left edge of the first bar. I want to make the xticks at the center
between the two bars to have a better visualization. I dnt get which
arguement i should use to get the xticks at the center of the two bars as in
the following example

http://matplotlib.sourceforge.net/examples/pylab_examples/barchart_demo.html

Thanks,
Bala

On 07/19/2010 03:11 PM, Clear wrote:
>
> plt.plot(x,np.sin(x),"-s",markevery=N/50)
>
> I have tried your option but a message is returned to me which says that
> markevery is an unknown property. I have included exactly the code you
> propose. May I guess why I am getting such error?
>
> Clear
>
>

Are you sure you ran the example as I sent it? markevery should be 
available since matplotlib version 0.98.5.2, released at the end of 
2008. Which mpl version and operating system are you using?

JLS

On Thu, Jul 15, 2010 at 2:44 PM, texas_ranger <dw...@gm...> wrote:

>
> The source code for radar_chart.py located in the Matplotlib docs at
>
>
> http://matplotlib.sourceforge.net/examples/api/radar_chart.html?highlight=radar%20chart
>
> does not work. Seems to be problem with legend.
>
> Can someone tell me what's wrong with the source code so I can correct my
> copy?
>
>
The version that is in svn trunk works fine for me, and it hasn't been
changed since last year.  I wonder what the document generator is crashing
on?

Ben Root

plt.plot(x,np.sin(x),"-s",markevery=N/50)

I have tried your option but a message is returned to me which says that
markevery is an unknown property. I have included exactly the code you
propose. May I guess why I am getting such error?

Clear


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Hi,

as you can see here (lotlib.sourceforge.net/api/ticker_api.html),
you need to set your formatter to either ScalarFormatter and set it up, so no 
offset is used or FormatStrFormatter with something like %d.


Kind regards,

Malte Dik

On 07/15/2010 02:36 PM, Clear wrote:
>
> Hello,
>
> I would like to know if it is possible to display the following feature
> using matplotlib. Say that you have a 2D plot(x,y) with a lot of data. You
> plot the data using a 2D solid line. Would be possible to add "some"
> circles/squared or whatever to the solid line? When I say "some" I mean only
> scattered values, otherwise given the quantity of data you would appreciate
> the symbols.
>
> Thanks,
>
> Clear

You can specify the parameter markevery=n to the plot to just plot every 
n-th marker. For example:

import matplotlib.pyplot as plt
import numpy as np
N = 10000
x = np.linspace(-10.0,10.0,N)
plt.plot(x,np.sin(x),"-s",markevery=N/50)
plt.show()


Regards,
João Luís

Hello,

When plotting high value on a very small range (i.e. y varies from 100.000 to 100.002), matplotlib automatically removes the 'high base value' (here 100.000) and displays it close to the axis. (you can find enclosed my picture of this example)
The very basic thing i want to do is to disable this smart formatter, and display the values from 100.000 to 100.002.

I think it's an easy thing to achieve, but i'm somehow lost in the jungle of instances and methods contained in the 'plot' library, and on top of it, i don't know the name of this operation ('y -= value' only for display).

For now i'm still using matplotlib 0.99, since yet v1.0 is not available with the FINK package-manager.

Thank in advance, for your answer and your time.

Geoffroy