matplotlib-users

[Matplotlib-users] Colorbar for pcolor plot

[marcusantonius <mar...@st...>]

Hi everybody, 
I have the problem, that I cannot add a color bar to a pcolor plot, which I
generate of some Data files. If I do
fig = plt.figure()

plot1 = fig.add_subplot(231,aspect='equal')
plot1.pcolor(xsr)
plot1.axis([0, 127, 0, 127])
plot1.colorbar()

it just gives me
AttributeError: 'AxesSubplot' object has no attribute 'colorbar'
WARNING: Failure executing file: <test.py>

What am I doing wrong? At the end of this file you find the whole plot-file

Thank you for your help,
Markus



#!usr/bin/python
# -*- coding: utf-8 -*-

import numpy as np
import matplotlib.pyplot as plt

# Open files

file1 = open('../physical/x-ray/193XM_phys.am', 'rb')
file1.seek(-131072,2) 
xm=np.fromfile(file1,dtype='>d')
file1.close()

file2 = open('../physical/x-ray/193XSB_phys.am', 'rb')
file2.seek(-131072,2)
xs=np.fromfile(file2,dtype='>d')
file2.close()

file3 = open('../physical/x-ray/193XT_phys.am', 'rb')
file3.seek(-131072,2)
xt=np.fromfile(file3,dtype='>d')
file3.close()

xsr=np.transpose(np.reshape(xs,(128,128)))
xtr=np.transpose(np.reshape(xt,(128,128)))
xmr=np.transpose(np.reshape(xm,(128,128)))

ind_xmax=np.where(xsr==np.max(xsr))[1][0]
ind_ymax=np.where(xsr==np.max(xsr))[0][0]

profil_xsr=np.zeros(np.minimum(ind_xmax,ind_ymax))
profil_xtr=np.zeros(np.minimum(ind_xmax,ind_ymax))
profil_xmr=np.zeros(np.minimum(ind_xmax,ind_ymax))
anzahl_gridpunkte=np.zeros(np.minimum(ind_xmax,ind_ymax))

for k in range(0,26):
    # Schleife über alle Gitterzellen
    for i in range(128):
	for j in range (128):
	    if  (k)**2 < (i-ind_ymax)**2+(j-ind_xmax)**2 <= (k+1)**2:
		profil_xsr[k]=profil_xsr[k]+xsr[i][j]
		profil_xtr[k]=profil_xtr[k]+xtr[i][j]
		profil_xmr[k]=profil_xmr[k]+xmr[i][j]
		anzahl_gridpunkte[k]=anzahl_gridpunkte[k]+1

profil_xsr=profil_xsr/anzahl_gridpunkte
profil_xtr=profil_xtr/anzahl_gridpunkte
profil_xmr=profil_xmr/anzahl_gridpunkte
    
fig = plt.figure()

plot1 = fig.add_subplot(231,aspect='equal')
plot1.pcolor(xsr)
plot1.axis([0, 127, 0, 127])
plot1.colorbar()

plot2 = fig.add_subplot(232,aspect='equal')
plot2.pcolor(10**xtr)
plot2.axis([1, 128, 1, 128])

plot3 = fig.add_subplot(233,aspect='equal')
plot3.pcolor(xmr,vmin=0.0,vmax=0.5)
plot3.axis([1, 128, 1, 128])



plot4 = fig.add_subplot(234)
plot4.plot(profil_xsr)
plot4.axis(ymin=0, ymax=10)


plot5 = fig.add_subplot(235)
plot5.plot(profil_xtr)
plot5.axis(ymin=0, ymax=10)

plot6 = fig.add_subplot(236)
plot6.plot(profil_xmr)
plot6.axis([0, 25,0, 1])

fig.show()



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Re: [Matplotlib-users] Colorbar for pcolor plot

[Ryan M. <rm...@gm...>]

On Wed, May 20, 2009 at 3:17 AM, marcusantonius <
mar...@st...> wrote:

>
> Hi everybody,
> I have the problem, that I cannot add a color bar to a pcolor plot, which I
> generate of some Data files. If I do
> fig = plt.figure()
>
> plot1 = fig.add_subplot(231,aspect='equal')
> plot1.pcolor(xsr)
> plot1.axis([0, 127, 0, 127])
> plot1.colorbar()
>
> it just gives me
> AttributeError: 'AxesSubplot' object has no attribute 'colorbar'
> WARNING: Failure executing file: <test.py>
>
> What am I doing wrong? At the end of this file you find the whole plot-file


Thanks for the full example, but if you carefully read the exception, it was
telling you the problem. :)  plot1 here is an axes object, which does not
have a colorbar() method.  Instead, you should change that to:

plt.colorbar()

Assuming everything else was working, you should be good to go with this
change.

Ryan

-- 
Ryan May
Graduate Research Assistant
School of Meteorology
University of Oklahoma
Sent from Norman, Oklahoma, United States

Re: [Matplotlib-users] Colorbar for pcolor plot

[John H. <jd...@gm...>]

On Wed, May 20, 2009 at 9:53 AM, Ryan May <rm...@gm...> wrote:

> Thanks for the full example, but if you carefully read the exception, it was
> telling you the problem. :)  plot1 here is an axes object, which does not
> have a colorbar() method.  Instead, you should change that to:
>
> plt.colorbar()
>
> Assuming everything else was working, you should be good to go with this
> change.
>

It looks like Markus is trying to use the API, so rather than suggest
the pyplot colorbar method, I suggest using the figure instance
method.  Markus the pyplot method plt.colorbar is a thin wrapper
around the figure method fig.colorbar -- see also:

  http://matplotlib.sourceforge.net/faq/usage_faq.html#matplotlib-pylab-and-pyplot-how-are-they-related

  http://matplotlib.sourceforge.net/api/figure_api.html#matplotlib.figure.Figure.colorbar

It may be a good idea and refer to the return value of fig.add_subplot
as "ax" or something that, rather than "plot1" because add_subplot
returns an Axes instance and thus ax is a better mnemonic; see

  http://matplotlib.sourceforge.net/api/figure_api.html#matplotlib.figure.Figure.add_subplot

So I suggest something like::

    fig = plt.figure()

    ax1 = fig.add_subplot(231,aspect='equal')
    ax1.pcolor(xsr)
    ax1.axis([0, 127, 0, 127])
    fig.colorbar()

JDH

Re: [Matplotlib-users] Colorbar for pcolor plot

[Markus H. <mar...@st...>]

Thank you very much for your detailed explanations. When I try

plot1 = fig.add_subplot(231,aspect='equal')
plot1.pcolor(xsr)
plot1.axis([0, 127, 0, 127])
plt.colorbar()
I get the error message
AttributeError: 'NoneType' object has no attribute 'autoscale_None'
WARNING: Failure executing file: <test.py>
But I don't really know, what this means.


> It may be a good idea and refer to the return value of fig.add_subplot
> as "ax" or something that, rather than "plot1" because add_subplot
> returns an Axes instance and thus ax is a better mnemonic; see
> 
Thank you very much, I was not aware of that. However, if I try

fig = plt.figure()
ax1 = fig.add_subplot(231,aspect='equal')
ax1.pcolor(xsr)
ax1.axis([0, 127, 0, 127])
fig.colorbar()
I also get an error message:
TypeError: colorbar() takes at least 2 arguments (1 given)
WARNING: Failure executing file: <test.py>

Cheers,
Markus

Re: [Matplotlib-users] Colorbar for pcolor plot

[Ryan M. <rm...@gm...>]

On Wed, May 20, 2009 at 10:04 AM, John Hunter <jd...@gm...> wrote:

> On Wed, May 20, 2009 at 9:53 AM, Ryan May <rm...@gm...> wrote:
>
> > Thanks for the full example, but if you carefully read the exception, it
> was
> > telling you the problem. :)  plot1 here is an axes object, which does not
> > have a colorbar() method.  Instead, you should change that to:
> >
> > plt.colorbar()
> >
> > Assuming everything else was working, you should be good to go with this
> > change.
> >
>
> It looks like Markus is trying to use the API, so rather than suggest
> the pyplot colorbar method, I suggest using the figure instance
> method.  Markus the pyplot method plt.colorbar is a thin wrapper
> around the figure method fig.colorbar -- see also:
>
>
> http://matplotlib.sourceforge.net/faq/usage_faq.html#matplotlib-pylab-and-pyplot-how-are-they-related
>
>
> http://matplotlib.sourceforge.net/api/figure_api.html#matplotlib.figure.Figure.colorbar
>
> It may be a good idea and refer to the return value of fig.add_subplot
> as "ax" or something that, rather than "plot1" because add_subplot
> returns an Axes instance and thus ax is a better mnemonic; see
>
>
> http://matplotlib.sourceforge.net/api/figure_api.html#matplotlib.figure.Figure.add_subplot
>
> So I suggest something like::
>
>    fig = plt.figure()
>
>    ax1 = fig.add_subplot(231,aspect='equal')
>    ax1.pcolor(xsr)
>    ax1.axis([0, 127, 0, 127])
>    fig.colorbar()


Except that it won't work like that. :) (I actually tried that the first
time) You need to give Figure.colorbar() the mappable as the first
argument.  So this would then become:

    ax1 = fig.add_subplot(231,aspect='equal')
    pc = ax1.pcolor(xsr)
    ax1.axis([0, 127, 0, 127])
    fig.colorbar(pc)

Ryan

-- 
Ryan May
Graduate Research Assistant
School of Meteorology
University of Oklahoma
Sent from Norman, Oklahoma, United States

Re: [Matplotlib-users] Colorbar for pcolor plot

[Markus H. <mar...@st...>]

Am Mittwoch, den 20.05.2009, 10:21 -0500 schrieb Ryan May:
> 
> Except that it won't work like that. :) (I actually tried that the
> first time) You need to give Figure.colorbar() the mappable as the
> first argument.  So this would then become:
> 
>     ax1 = fig.add_subplot(231,aspect='equal')
>     pc = ax1.pcolor(xsr)
>     ax1.axis([0, 127, 0, 127])
>     fig.colorbar(pc)

Yep, that's it. It works now. Thank you for your help,

Cheers,
Markus