matplotlib-devel Mailing List for matplotlib

Eric,
I played with the changes you've made and the results look great!
Thanks,
Gerald
Eric Firing wrote:
> John,
> 
> I have committed to CVS a set of changes that I think will address 
> recent requests by Jordan and Gerald, and will be of more general use as 
> well. From the CHANGELOG:
> 
> 2005年11月27日 Multiple changes in cm.py, colors.py, figure.py, image.py,
> contour.py, contour_demo.py; new _cm.py, 
> examples/image_masked.py.
> 1) Separated the color table data from cm.py out into
> a new file, _cm.py, to make it easier to find the actual
> code in cm.py and to add new colormaps. Also added
> some line breaks to the color data dictionaries. Everything
> from _cm.py is imported by cm.py, so the split should be
> transparent.
> 2) Enabled automatic generation of a colormap from
> a list of colors in contour; see modified
> examples/contour_demo.py.
> 3) Support for imshow of a masked array, with the
> ability to specify colors (or no color at all) for
> masked regions, and for regions that are above or
> below the normally mapped region. See
> examples/image_masked.py.
> 4) In support of the above, added two new classes,
> ListedColormap, and no_norm, to colors.py, and modified
> the Colormap class to include common functionality. Added
> a clip kwarg to the normalize class. Reworked color
> handling in contour.py, especially in the ContourLabeller
> mixin.
> 
> With one very subtle exception, I don't think any default behaviors have 
> been changed, so the changes should be entirely non-disruptive.
> 
> That one exception is that in the original color mapping scheme, the 
> last color was essentially never used. Consider an extreme case: a 
> colormap with two entries. Suppose the image data ranged from 0 to 1. 
> All values except exactly 1.0 were mapped to the first color, and only 
> that upper limit value was mapped to the second color. As I have 
> changed colors.py, values from 0.0 up to 0.5 will get the first color, 
> and values from 0.5 through 1.0 will get the second. I think this is 
> what a user would expect, and the only reason it hasn't mattered is that 
> with 256 colors in a continuous range, one can't see the difference.
> 
> The request from Jordan that is addressed here is the desire for precise 
> color control in filled contouring. Now one can specify a list of 
> colors in the "colors" kwarg, and they will be used to generate a 
> colormap, which will then be used by colorbar. This is shown in a 
> second plot added to examples/contourf_demo.py. (Jordan suggested a 
> more extensive refactoring, which may indeed be a good idea; but I 
> wanted to make these simpler changes before trying to think about 
> anything more drastic.)
> 
> The request from Gerald was for easy handling of masked arrays in 
> imshow. It was in the context of basemap, which I have not tested yet; 
> but at least for pylab.imshow, the situation is now easy to handle. If 
> changes to basemap are needed, they should be very simple, and I can do 
> them later as needed. I think that the changes to colormapping that I 
> made to support this will be useful much more widely, but I have made no 
> attempt to track down the places where changes will be in order. I may 
> make additional changes to contour, and I know I will need to change 
> colorbar to fully support this. I think colorbar needs some more 
> refactoring anyway, but I can't do it immediately, and I did not want to 
> delay getting the other changes out for testing and, hopefully, 
> productive use.
> 
> Eric
> 
> 
>