Question

I have a typical scenario in which there is a Vector X and Vector Y. Vector X contains increasing values, for example X = [1 1 1 2 2 3 4 4 4 4 4]. Vector Y contains real values of same size as X. Im looking to plot Index Vs Y with color change for each different value of X for the corresponding index.

For example, the plot should have color1 for the first 3 values of 1, color2 for the next 2 values of 2, color3 for 1 value 3 and so on.

Can any one help me

Answer 1

Building on Laurent’s answer and implementing your “Index vs Y” requirement,

function color_plot(data_vector, color_vector)
styles={'ro','g.','bx','kd'};
hold off;
for i=unique(color_vector)
    thisIdx=find(color_vector==i);
    thisY=data_vector(color_vector==i);
    thisStyle=styles{mod(i-1,numel(styles))+1}; 
    plot(thisIdx,thisY,thisStyle);
    hold on;
end
hold off;

My version also allows arbitrarily large color indices; if you don’t have enough styles defined, it just wraps back around and reuses colors.

Update note I had to fix a sign above in the calculation oh thisStyle.

Testing it with

X = [1 1 1 2 2 3 4 4 4 4 4];
Y=rand(size(X))
color_plot(Y,X)

now gives