matplotlib-users Mailing List for matplotlib

Hello all,
I've stumbled onto a bug in colorbar() when displaying an image with a 
nonlinear normalization (using a recent CVS version of mpl). If one 
subclasses matplotlib.colors.normalize and uses a nonlinear function in the 
__call__() method, then colorbar() will mismatch colors and data values in 
the colorbar.
Some code illustrating a test case is attached. Here, I use the sqrt() 
function to normalize some data in the domain (0, 10) to the range (0, 1) 
[f(x)=sqrt(x/10)]. I display an image which consists of a linear ramp, each 
value given by the abcissa. The normalization function y=f(x) is overplotted 
for reference. imshow() applies the normalization before looking up the 
colormap value, as expected (colors are bunched to the left). However, note 
the values in the colorbar annotation do not correspond to the data values! 
For example, pre-normalization data value 4 (x-axis) is correctly colored as 
yellow, however the color bar erroneously lists that value as cyan (which is 
the color where y=4/10=.4).
The error is that colorbar() assumes linearity over the normalization domain. 
Ultimately, I think I'd like a choice as to whether to stretch colors in the 
colorbar with a linear sampling of the data domain, or keep the color 
sequence linear and invert the normalization step to determine the tick 
values. Has anyone encountered and/or coded a solution for this?
Thanks,
Mike

On 2006年1月15日, Nils Wagner apparently wrote: 
> I was wondering whether you could provide me with a reference concerning 
> the citation of matplotlib. 
> http://www.scipy.org/documentation/citingscipy.html 
http://www.nabble.com/Re%3A-How-to-cite-matplotlib-p1921205.html
hth,
Alan Isaac

Hi John,
I was wondering whether you could provide me with a reference concerning
the citation of matplotlib.
http://www.scipy.org/documentation/citingscipy.html
Thanks in advance
 Nils

Hey, 
 Luckily, I can still save the output graph into png with a command, but the Save button on the output is not working; in fact, none of the clicking buttons are working on the output graph. Does anyone know how to fix this? 
 
 sincerely, 
 Jerry
 
 
 
		
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