Plot a 2-dimensional matrix with 2 different colormaps for negative and positive values

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THONTI BEERAIAH
THONTI BEERAIAH 2023-8-25
评论： Dyuman Joshi 2023-8-28
I have a big matrix consisting of values ranging from negative to positive. When I plot that by just imagesc and apply colorbar it is shpwoing gradiant over all. My requirement is to apply one colormap for negative values (probably cool) and the other colormap for positive values (probabliy hot) in a same plot as attached ( so there will be clear difference between negative and positive values).

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Dyuman Joshi
Dyuman Joshi 2023-8-25
编辑：Dyuman Joshi 2023-8-25
Ran in:
%Random data for example
y = (-7:5)+(-7:5)';
%Get the maximum and minimum values of the array
p = max(y,[],'all');
n = min(y,[],'all');
%Display via imagesc
imagesc(y)
%Two colormaps
col = [cool(abs(n));hot(p)];
%Multiply the input with the same number to get more divisions on colors
%col = [cool(3*abs(n));hot(3*p)];
cb = colorbar('Ticks',n:p);
colormap(col)
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THONTI BEERAIAH
THONTI BEERAIAH 2023-8-28
Thank you, however you solution worked nice for matrix with integers. I have a matrix which has noninteger values where the method is not working. I am uploading one matrix (as text file) so could you please do the same for the uploaded data?
Dyuman Joshi
Dyuman Joshi 2023-8-28
Ran in:
For non-integer values, round the values away from zero -
%Random data for example
vec = (-7.5:0.5:5);
y = vec+vec';
%Get the maximum and minimum values of the array
p = max(y,[],'all');
n = min(y,[],'all');
%As the input to colormaps must be positive (because it's an index)
%to round away from zero, we take ceil() of the absolute value
f = @(x) ceil(abs(x));
%Display via imagesc
imagesc(y)
%Two colormaps
col = [cool(f(n));hot(f(p))];
cb = colorbar('Ticks',n:p);
colormap(col)

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