Is it possible to overlay pcolor plots using hold on?

I was trying to overlay pcolor plots using hold on but I get the following error "Error using colormap (line 61) First argument must be a scalar axes or figure handle".

Any idea on what might be going wrong? Thanks

f1 = figure(Visible="on");
    Y=pcolor(T,H, A');   
    set(Y, 'EdgeColor', 'none');
    set(gca,'ColorScale','log');
    hold on
    Z=pcolor(T,H, abs(B'));
    set(Z, 'EdgeColor', 'none');
     set(gca,'ColorScale','log');
   

     cmp1 = colormap(jet);
    cmp1 = [1 1 1;cmp1];

    cmp2 = colormap("parula");
    cmp2 = [1 1 1;cmp2];
    colormap(Y,cmp1);
    colormap(Z,cmp2);
    hold off

Answer 1

[Walter Roberson]

    colormap(Y,cmp1);

If you pass in more than one positional parameter to colormap, then the first parameter must be an axes.

It is not possible to colormap() individual pcolor() objects.

You can however use rescale() (or the earlier mat2gray()) to convert the input values to the 0 to 1 range, multiply by the number of colors in the color map, floor(), uint8(), and then ind2rgb() against the colormap, in order to get an RGB equivalent. Or use the FIle Exchange contribution Freeze Colors.

Answer 2

[Highphi]

f1 = figure;% (Visible="on");
Y = pcolor(T, H, A');   
set(Y, 'EdgeColor', 'none');
set(gca,'ColorScale','log');
hold on

cmp1 = colormap(jet);
cmp1 = [1 1 1;cmp1];
set(gca, 'Colormap', cmp1)


Z = pcolor(T, H, abs(B'));
set(Z, 'EdgeColor', 'none');
set(gca,'ColorScale','log');
   
cmp2 = colormap("parula");
cmp2 = [1 1 1;cmp2];
set(gca, 'Colormap', cmp2);
hold off

[Walter Roberson]

You are using the same axes both times there, but any one axes can only have one colormap.

See the File Exchange contribution FreezeColors()