www.gusucode.com > graphics 案例源码程序 matlab代码 > graphics/ExcludeNegativeDataValuesFromColormapExample.m

    %% Change Mapping of Data Values into Colormap
% This example shows how to control the mapping of data values to colors in
% the colormap so that negative data values map to black.

% Copyright 2015 The MathWorks, Inc.

 
%%
% Create |X|, |Y|, and |Z| as 30-by-30 arrays from the |peaks| function.
% Use the arrays to plot a surface. Use |Z| for both the surface height and
% the color data. Add a colorbar that shows how the color data values map
% to colors in the colormap.
 
[X,Y,Z] = peaks(30);
surf(X,Y,Z)
colorbar
 
%%
% Return the current color limits of the axes, |cmin| and |cmax|. Color
% data values less than or equal to |cmin| map to the first color in the
% colormap. Values greater than or equal to |cmax| map to the last color in
% the colormap.
 
[cmin,cmax] = caxis
 
%% 
% Change the color limits using |caxis| again. Set the minimum color limit
% to |0| so that values of |0| or less map to the first color in the
% colormap. Keep the same maximum color limit.
 
caxis([0,cmax])
 
%%
% Return the current colormap as |map|. Set the first color in the colormap
% to black by setting the first row of |map| to |[0 0 0]|. Apply the
% updated colormap to the figure.
 
map = colormap; 
map(1,:) = [0 0 0]; 
colormap(map) 
 
 
%%
% All data values less than or equal to |0| map to black.