plot shifting while using histcounts

Hi,

I'm trying to compare 2 spectrums but I get this shifting in the X-axis (the blue spectrum is processed data out the red one), my suspition is that it happened since I'm using histocounts.

this is the plot script:

[X,~] = histcounts(X_table.energy,2744);

semilogy(X,'r')

% xlim([1 2000])

hold on

[Z,~] = histcounts(Y,2744);

semilogy(Z,'b')

% xlim([1 2000])

Answer 1

[Rik]

You are specifying the number of bins, not the exact bins. Then when you are plotting you don't specify the x-value. If you change either of these the data should align again.

[sani]

Hi Rik, thanks for your answer.

I didn't quite understand what you mean by exact bins, can you give an example?

[Rik]

Did you read the documentation for the histcounts function? You can either provide the number of bins, or the edges of those bins. If you use the code below, you re-use the same bin edges for both calls.

[X,edges] = histcounts(X_table.energy,2744);
Z = histcounts(Y,edges);

bincenters=edges(2:end)-0.5*diff(edges(1:2));
semilogy(bincenters,X,'r')
hold on
semilogy(bincenters,Z,'b')

[sani]

thanks a lot!

I did read the documentation but didn't understand the that I need to use edges.

[Rik]

Well, you don't need to, but if you want to compare two sets of data you should be using the same bins, so you can't let Matlab figure out the bins automatically.