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gyacomo/matlab/bluewhitered.m
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bluewhitered.m
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function newmap = bluewhitered(m)
%BLUEWHITERED Blue, white, and red color map.
% BLUEWHITERED(M) returns an M-by-3 matrix containing a blue to white
% to red colormap, with white corresponding to the CAXIS value closest
% to zero. This colormap is most useful for images and surface plots
% with positive and negative values. BLUEWHITERED, by itself, is the
% same length as the current colormap.
%
% Examples:
% ------------------------------
% figure
% imagesc(peaks(250));
% colormap(bluewhitered(256)), colorbar
%
% figure
% imagesc(peaks(250), [0 8])
% colormap(bluewhitered), colorbar
%
% figure
% imagesc(peaks(250), [-6 0])
% colormap(bluewhitered), colorbar
%
% figure
% surf(peaks)
% colormap(bluewhitered)
% axis tight
%
% See also HSV, HOT, COOL, BONE, COPPER, PINK, FLAG,
% COLORMAP, RGBPLOT.
if nargin < 1
m = size(get(gcf,'colormap'),1);
end
bottom = [0 0 0.5];
botmiddle = [0 0.5 1];
middle = [1 1 1];
topmiddle = [1 0 0];
top = [0.5 0 0];
% Find middle
lims = get(gca, 'CLim');
% Find ratio of negative to positive
if (lims(1) < 0) & (lims(2) > 0)
% It has both negative and positive
% Find ratio of negative to positive
ratio = abs(lims(1)) / (abs(lims(1)) + lims(2));
neglen = round(m*ratio);
poslen = m - neglen;
% Just negative
new = [bottom; botmiddle; middle];
len = length(new);
oldsteps = linspace(0, 1, len);
newsteps = linspace(0, 1, neglen);
newmap1 = zeros(neglen, 3);
for i=1:3
% Interpolate over RGB spaces of colormap
newmap1(:,i) = min(max(interp1(oldsteps, new(:,i), newsteps)', 0), 1);
end
% Just positive
new = [middle; topmiddle; top];
len = length(new);
oldsteps = linspace(0, 1, len);
newsteps = linspace(0, 1, poslen);
newmap = zeros(poslen, 3);
for i=1:3
% Interpolate over RGB spaces of colormap
newmap(:,i) = min(max(interp1(oldsteps, new(:,i), newsteps)', 0), 1);
end
% And put 'em together
newmap = [newmap1; newmap];
elseif lims(1) >= 0
% Just positive
new = [middle; topmiddle; top];
len = length(new);
oldsteps = linspace(0, 1, len);
newsteps = linspace(0, 1, m);
newmap = zeros(m, 3);
for i=1:3
% Interpolate over RGB spaces of colormap
newmap(:,i) = min(max(interp1(oldsteps, new(:,i), newsteps)', 0), 1);
end
else
% Just negative
new = [bottom; botmiddle; middle];
len = length(new);
oldsteps = linspace(0, 1, len);
newsteps = linspace(0, 1, m);
newmap = zeros(m, 3);
for i=1:3
% Interpolate over RGB spaces of colormap
newmap(:,i) = min(max(interp1(oldsteps, new(:,i), newsteps)', 0), 1);
end
end
%
% m = 64;
% new = [bottom; botmiddle; middle; topmiddle; top];
% % x = 1:m;
%
% oldsteps = linspace(0, 1, 5);
% newsteps = linspace(0, 1, m);
% newmap = zeros(m, 3);
%
% for i=1:3
% % Interpolate over RGB spaces of colormap
% newmap(:,i) = min(max(interp1(oldsteps, new(:,i), newsteps)', 0), 1);
% end
%
% % set(gcf, 'colormap', newmap), colorbar
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