MATLAB: Colouring Bars by ‘Y’ value

bar chartcolouringMATLAB

Hello Community,
I am trying to plot a bar chart and to colour the bars according to a rule related to the values for the 'Y' axis. So, if the Y value is a minus figure, the bar should be coloured grey, and if positive, should be coloured black. I have tried the following (and several variations):
% Colouring bars
if y <0;
    bar(y,'RGB::Grey');
elseif y >= 0;
    bar(y,'RGB::Black');
end
but with no luck. Everything else about the plotting that I am doing works fine.
I'm sure this will be simple for the more experienced, so could anyone suggest a fix to help me please?
Thank you,
10B.

Best Answer

I would suggest the approach I described in this blog post. In this case, it would look something like this:
x = 1:18;
y = randn(1,18);
mask = y > 0;
y1 = y;
y1(mask) = nan;
bar(x,y1,'FaceColor','red')
hold on
y2 = y;
y2(~mask) = nan;
bar(x,y2,'FaceColor','green')
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