How to do combination of color in a single colorbar in a scatter plot?

I have one data set of 4964 values "s" varible with latitude and longitude. I want to plot all the positive values with red color (gradually shaded color) using "BREWERMAP Function" link provided. Zero Values in Green color and negative values in blue (Not shaded fix color). Tried many things couldn't able get a desired output. The figure should have a single colorbar. Tried using different axis, but that generate 3 colorbar. Any help will be appreciated.

https://in.mathworks.com/matlabcentral/fileexchange/45208-colorbrewer-attractive-and-distinctive-colormaps

Code

scatter(lon,lat,6,s,"filled");

Answer 1

[Voss]

Maybe something like this.

load Data

reds = brewermap([],'Reds');
green = [0 1 0];
blue  = [0 0 1];

smax = max(s(:));
nr = size(reds,1);
ng = 2;
nb = floor(nr/25);

c = zeros(numel(s),3);

idx = s > 0;
c(idx,:) = reds(ceil(s(idx)*nr/smax),:);

idx = s == 0;
c(idx,:) = repmat(green,nnz(idx),1);

idx = s < 0;
c(idx,:) = repmat(blue,nnz(idx),1);

scatter(lon,lat,6,c,"filled");

colormap([repelem([blue; green],[nb,ng],1); reds])
clim([-(nb+ng/2)/(nr+ng/2),1]*smax)
colorbar()

[Avijit Paul]

Thanks a lot, Perfect, was trying a lot for this output.

[Voss]

You're welcome!