matplotlib-users Mailing List for matplotlib

Does anyone have an example of nested grids.

I need to (for instance), plot a global grid in filled contours, then plot
another, higher resolution grid over the US.
The global grid could work something like this, but I'm not sure where to
start with the 2nd (nested) grid to go atop.

fig=plt.figure()
m = Basemap(resolution='c',projection='cyl',llcrnrlon=lon1,llcrnrlat=lat1,\
            urcrnrlon=lon2,urcrnrlat=lat2)
# make a filled contour plot.
x, y = m(lons, lats)
CS = m.contour(x,y,hgt,15,linewidths=0.5,colors='k')
CS = m.contourf(x,y,hgt,15,cmap=plt.cm.jet)
m.drawcoastlines()
m.drawmapboundary()
m.fillcontinents()
# draw parallels and meridians.
parallels = np.arange(-90,90,10)
#m.drawparallels(parallels,labels=[1,0,0,1])
m.drawparallels(parallels,labels=[1,0,0,1])
meridians = np.arange(-180.,180.,10.)
m.drawmeridians(meridians,labels=[1,0,0,1])
plt.title('Plotted Grid')
plt.show()

Thanks!

Bruce

---------------------------------------
Bruce W. Ford
Clear Science, Inc.
br...@cl...

On 06/06/2011 11:33 AM, Daniel Mader wrote:
> Hi all,
>
> I'd like to compare two sets of data by using subplots and imshow(). I
> have two issues with this:
>
> 1) how can I have a colorbar in each subplot?
> 2) how can I adjust the range limits for a colorbar, so that the
> comparison possible?
>
> Below is code which could serve as a starting point, I hope it helps
> to make my problem clearer...

It's not quite clear to me yet, but I assume you want to use a call to 
imshow with a different data set in the second subplot, but have the 
color scale and colorbar be identical to those in the first subplot.  Is 
that correct?  If so, all you need to do is use the same norm for both 
calls to imshow--that is, define a norm, set the limits you want on it, 
and supply it as a kwarg.

Also, for this sort of comparison, sometimes it is more efficient to use 
a single colorbar for multiple panels, as in this example:

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

Eric

>
> Thanks and best regards,
> Daniel
>
> import pylab
> #import matplotlib as mpl
> import matplotlib.cm as cm # colormaps
> #import matplotlib.colors as col # colormaps
>
> pylab.close('all')
>
> dat = pylab.array([[1,2,3,4],[5,6,7,8]])
> datT = dat/2
>
> fig = pylab.figure()
>
> ax1 = fig.add_subplot(211)
> ax1.set_title('raw data')
> im = ax.imshow(dat, interpolation='nearest', cmap=cm.get_cmap('rainbow', 20))
> fig.colorbar(im)
>
> ax2 = fig.add_subplot(212)
> ax2.set_title('transformed')
> ''' here is missing:
> a 2nd colorbar with the same limit than in the first subfig, i.e. 1..8
> '''
>
> pylab.show()
>
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Hi all,

I'd like to compare two sets of data by using subplots and imshow(). I
have two issues with this:

1) how can I have a colorbar in each subplot?
2) how can I adjust the range limits for a colorbar, so that the
comparison possible?

Below is code which could serve as a starting point, I hope it helps
to make my problem clearer...

Thanks and best regards,
Daniel

import pylab
#import matplotlib as mpl
import matplotlib.cm as cm # colormaps
#import matplotlib.colors as col # colormaps

pylab.close('all')

dat = pylab.array([[1,2,3,4],[5,6,7,8]])
datT = dat/2

fig = pylab.figure()

ax1 = fig.add_subplot(211)
ax1.set_title('raw data')
im = ax.imshow(dat, interpolation='nearest', cmap=cm.get_cmap('rainbow', 20))
fig.colorbar(im)

ax2 = fig.add_subplot(212)
ax2.set_title('transformed')
''' here is missing:
a 2nd colorbar with the same limit than in the first subfig, i.e. 1..8
'''

pylab.show()

I found a solution after all, from 
http://old.nabble.com/_backend_gdk-not-found-td26514059.html#a26514059 the
thread  I mentioned in the original post, which turned out not to be as
cryptic as I had thought.


Just as the answerer there suggested, I had PyGTK but matplotlib wasn't
recognizing it during build; when I tried building from source instead of
using macports this was made clear in the build output.


As he said, I searched my computer to find a file called pygtk-2.0.pc, and
added the directory it was in to the system variable PKG_CONFIG_PATH. After
I did that, the build was successful and I had no further problems!


Thanks to everyone who may have read my post, but I would up figuring this
one out on my own.





thecommexokid wrote:
> 
> 
Hi all,

> 
> 
I am new to the forum and to all things PyGTK and matplotlib, so go easy on
me, please.

> 
> 
A colleague created a Python program that uses matplotlib and GTK. I wanted
to be able run her program on my MacBook (OS X 10.6.7). I used macports to
update/obtain Python 2.7, matplotlib 1.0.1, and PyGTK 2.22.0. (I also
obtained ipython, if anyone cares.)

> 
> 
After all of this, my colleague's program hits a snag when I try to run it;
here is the traceback:

> 
> 
Traceback (most recent call last):
> 
  File "main.py", line 5, in 
> 
    from interface import Interface, Display, Controls
> 
  File
"/Users/thecommexokid/Documents/CurrentProjects/Honors/DoubleSlit/interface.py",
line 5, in <module>
> 
    from matplotlib.backends.backend_gtkagg import
FigureCanvasGTKAgg
> 
  File
"/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/backends/backend_gtkagg.py",
line 10, in <module>
> 
    from matplotlib.backends.backend_gtk import gtk,
FigureManagerGTK, FigureCanvasGTK,\
> 
  File
"/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/backends/backend_gtk.py",
line 28, in <module>
> 
    from matplotlib.backends.backend_gdk import
RendererGDK, FigureCanvasGDK
> 
  File
"/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/backends/backend_gdk.py",
line 29, in <module>
> 
    from matplotlib.backends._backend_gdk import
pixbuf_get_pixels_array
> 
ImportError: No module named _backend_gdk

> 
> 
I believe I may be having the same problem as the user in 
http://old.nabble.com/_backend_gdk-not-found-td26514059.html#a26514059 this
post , but I am enough of a novice that the solution that was suggested
there just sounds like gobbletygook to me. If anybody wants to elaborate on
that so I can try it out, please do.

> 
> 
Anyhow, any advice anyone has on how to overcome this problem and get her
program running on my machine would be greatly appreciated. As I said, I am
new to these things, and I don't really understand the interplay between
Python, PyGTK, and matplotlib, so if there's crucial information I haven't
provided, or if this isn't the best forum in which to be asking this
question, let me know.

> 
> 
Thanks in advance for the help.

> 
> 
***

> 
> 
PS: I originally posted this question at the GTK+ Forums (
http://www.gtkforums.com/viewtopic.php?f=3&p=69969#p69969 thread ), but it
seemed as though this might be the more appropriate forum. I'll be sure to
keep both threads updated with any developments.

> 

-- 
View this message in context: http://old.nabble.com/ImportError-when-I-import-FigureCanvasGTKAgg%E2%80%94seeking-advice%21-tp31779648p31785774.html
Sent from the matplotlib - users mailing list archive at Nabble.com.

Benjamin,

Thanks. I will point out that the contourf in Basemap behaves differently than that contourf in pylab. That is, in pylab, for
contour(X,Y,Z)
X,Y can be 1D whereas Z must be 2D.

However, it appears that for contourf in Basemap:

from mpl_toolkits.basemap import Basemap
m=Basemap()
g=m.contourf(X,Y,Z)

X,Y and Z must all be 2D.

-Tony

--
Tony Mannucci
Supervisor, Ionospheric and Atmospheric Remote Sensing Group
 Mail-Stop 138-308,                     Tel > (818) 354-1699
 Jet Propulsion Laboratory,              Fax > (818) 393-5115
 California Institute of Technology,     Email > Ton...@jp...<mailto:Ton...@jp...>
 4800 Oak Grove Drive,                   http://genesis.jpl.nasa.gov
 Pasadena, CA 91109


From: Benjamin Root <ben...@ou...<mailto:ben...@ou...>>
Date: Tue, 31 May 2011 08:50:22 -0700
To: Tony Mannucci <Ant...@jp...<mailto:Ant...@jp...>>
Cc: "mat...@li...<mailto:mat...@li...>" <mat...@li...<mailto:mat...@li...>>
Subject: Re: [Matplotlib-users] Input array dimensions for contour or contourf



On Tue, May 31, 2011 at 10:34 AM, Mannucci, Anthony J (335G) <ant...@jp...<mailto:ant...@jp...>> wrote:
The following program seems to work with contour/contourf. However the documentation for the contourf function states

contour(X,Y,Z)

"X, Y, and Z must be arrays with the same dimensions."

I am finding that contour works if the dimension of X and Y are 1, but Z must be two-dimensional. The following program seems to bear this out. Are the arrays x and y below two-dimensional, or is the documentation misleading? Thanks for your help.

import numpy as N
import pylab as PLT

lons = N.linspace(-5.,5.,5) # Is this a one or two dimensional array?
lats = N.linspace(-3.,3.,4)

z = N.zeros((len(lats), len(lons)))
for i in range(len(lons)):
    for j in range(len(lats)):
        z[j,i]=i+j

PLT.clf()
PLT.contourf(lons,lats,z)
PLT.colorbar()
PLT.show()

-Tony


Tony,

contour and contourf seems to take advantage of numpy's broadcasting feature, so it is probably more correct to say that X and Y must be at least broadcastable to the shape of Z.  I think there are a number of functions where this may or may not be true, and at some point we (the developers) should agree on basic input array handling and make it consistent across all plotting functions.

So, technically speaking, the docs are "right", but should be clearer in this case.  I will add it to my doc-fixing commit that I will do today.

Ben Root