change color for specifics bars

I have this code to create bar plot. but I would like to change color for specifics bars.

On the base of index, I would like that data with index (in xlabel) < 16 have to be red, >16 green, <5 blu and index ==16 green and ==8 blu

How can I do?

%Order table
z = sortrows(table,'variable','ascend'); 
%X
x = z.variable;
idxx=(1:20)'
x=z.variable(idxx)
%Y
y= z.variable1;
idxy=(1:20)'
y=z.variable1(idxy)

M2=[x y]

h=bar(idxx,M2(:,2))
h.FaceColor='flat';

xticks(1:numel(x))
xticklabels(x)
hAx=gca;
hAx.XTickLabelRotation=0;
%target
labels = categorical(z.textvariable);
xt = get(gca, 'XTick');
set(gca,'xticklabel',x)
text(xt, y, labels, 'HorizontalAlignment','center', 'VerticalAlignment','bottom')
%title
title('title')
xlabel('labelx','FontSize',14)
ylabel('labely','FontSize',14)
%legend
legend({'name',},'Location','northeast','Orientation','vertical')
lgd = legend;
lgd.FontSize = 14;

Answer 1

[Dave B]

I didn't fully understand your explanation of which colors you want where, but really all you have to do is set CData as you like it - there's one row for each bar and the columns a red, green, and blue (ranging from 0 to 1):

x = (1:20)';
y = rand(20,1);
h=bar(x,y);
h.FaceColor='flat';
ind = 1:20;

redind = ind < 16 & ind >=5;
greenind = ind >= 16;
blueind = ind < 5 | ind == 8;

h.CData(redind, :) = repmat([1 0 0],sum(redind),1);
h.CData(greenind, :) = repmat([0 1 0],sum(greenind),1);
h.CData(blueind, :) = repmat([0 0 1],sum(blueind),1);