On 04/09/2012 08:17 AM, Mathew Topper wrote: > Hi Eric, thanks for the tip about the legend. > > Regarding the data, assuming i am using pcolor, am I right in thinking > that using Boundarynorm would be the best way to control the colors for > each code?
Mat, I think BoundaryNorm is overkill and/or awkward for your case. It sounds like you don't have ordinary values, but rather a set of labels that happen to be integers. I would use a ListedColormap and then use sequential integers as the C values to index directly into the colormap: C = np.array([[0,1,2],[2,0,1]]) import matplotlib.colors as mcolors cmap = mcolors.ListedColormap(['r', 'g', 'lightgray']) pcolor(C, cmap=cmap, norm=mcolors.NoNorm()) Of course you would need to map your sequence of numbers (-8888, 0, ...) to a sequence of integers starting at zero. The key point is that the NoNorm() instance leaves your original C values alone, and since they are integers, they are then used directly as indices. You could also make your own mcolors.Normalize subclass which would process your labels and return either a float in the 0-1 range, or an integer for direct indexing. When you need only a very few colors, the ListedColormap with direct indexing is nice because it allows you to specify those colors using any valid color specification method. Eric > > Thanks > > Mat > > On 04/09/2012 06:26 PM, Eric Firing wrote: >> On 04/09/2012 02:22 AM, Mathew Topper wrote: >>> Dear matplotlib-users, >>> >>> I have a spatial data set that has coded values for each cell, which are >>> limited to just a few numbers, ie -8888, 0, 100, and 9999. I would like >>> to display this data with a plot similar to pcolor, but I don't want a >>> colorbar, I want a legend showing the colors for each code and an >>> explanation for what each code represents. I would like to be able to >>> choose a subset of the codes as well, for example just plotting the 0 >>> and 100 codes and ignoring the -8888 and 9999 codes. >>> >>> I have seen a few similar attempts that used BoundaryNorm, but I don't >>> want to show a range of values I just want to set colors for a few >>> explicit values. Those examples also had a colorbar and, as I said, I >>> would prefer a legend. >>> >>> Can anyone offer any tips? >> For the plot itself you can use pcolor if your data are on a >> quadrilateral grid, or a PathCollection or PolyCollection otherwise. >> For the legend, you can use proxy artists: >> >> http://matplotlib.sourceforge.net/users/legend_guide.html#using-proxy-artist >> >> Eric >> >>> Thanks >>> >>> Mat >>> >> >> ------------------------------------------------------------------------------ >> For Developers, A Lot Can Happen In A Second. >> Boundary is the first to Know...and Tell You. >> Monitor Your Applications in Ultra-Fine Resolution. Try it FREE! >> http://p.sf.net/sfu/Boundary-d2dvs2 >> _______________________________________________ >> Matplotlib-users mailing list >> Matplotlib-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/matplotlib-users >> > > -- > Dr. Mathew Topper > Institute for Energy Systems > School of Engineering > The University of Edinburgh > Faraday Building > The King’s Buildings > Edinburgh EH9 3JL > Tel: +44 (0)131 650 5570 > School fax: +44 (0)131 650 6554 > mathew.top...@ed.ac.uk <mailto:mathew.top...@ed.ac.uk> > http://www.see.ed.ac.uk <http://www.see.ed.ac.uk/> > > > > The University of Edinburgh is a charitable body, registered in > Scotland, with registration number SC005336. > > > > ------------------------------------------------------------------------------ > For Developers, A Lot Can Happen In A Second. > Boundary is the first to Know...and Tell You. > Monitor Your Applications in Ultra-Fine Resolution. Try it FREE! > http://p.sf.net/sfu/Boundary-d2dvs2 > > > > _______________________________________________ > Matplotlib-users mailing list > Matplotlib-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/matplotlib-users ------------------------------------------------------------------------------ For Developers, A Lot Can Happen In A Second. Boundary is the first to Know...and Tell You. Monitor Your Applications in Ultra-Fine Resolution. Try it FREE! http://p.sf.net/sfu/Boundary-d2dvs2 _______________________________________________ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
