2010/3/27 Ariel Rokem <aro...@berkeley.edu>: > I am trying to make a color-map which will respond to the range of values in > the data itself. That is - I want to take one of the mpl colormaps and use > parts of it, depending on the range of the data. > > In particular, I am interested in using the plt.cm.RdYlBu_r colormap. If the > data has both negative and positive values, I want 0 to map to the central > value of this colormap (a pale whitish yellow) and I want negative values to > be in blue and positive numbers to be in red. Also - I would want to use the > parts of the colormap that represent how far away the smallest and largest > values in the data are from 0. So - if my data is in the range [x1,x2] I > would want to use the part of the colormap in indices > 127-127*abs(x1)/(x2-x1) through 127+127*x2/(x2-x1). If the data only > includes positive numbers, I would want to only use the blue part of the > colormap and if there are negative numbers, I would want to only use the red > part of the colormap (in these cases, I would also want to take only a > portion of the colormap which represents the size of the interval [x1,x2] > relative to the interval [0,x1] or [x2,0], as the case may be). > > I think that this might be useful when comparing matrices generated from > different data, but with the same computation, such as correlation or > coherence (see http://nipy.sourceforge.net/nitime/examples/fmri.html to get > an idea of what I mean).
I might miss something important, but why not use pcolor() with kwargs vmin and vmax, http://matplotlib.sourceforge.net/api/axes_api.html#matplotlib.axes.Axes.pcolor, e.g.: maxval = numpy.abs(C).max() pcolor(C, vmin = -maxval, vmax = maxval) As far as I can judge, this should have the desired effect. Friedrich ------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev _______________________________________________ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
