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matlabhistogramedges

Dimensions of hist3 output

I have this code:

a = [1 1 1 3 3 5];
b = [1 3 3 3 5 5];
edges{1} = [0 2 4 6];
edges{2} = [0 2 4 6];
edges = edges';
h = hist3([a' b'],'Edges',edges)

The output h is 4x4 matrix,

 1     2     0     0
 0     1     1     0
 0     0     1     0
 0     0     0     0

However I think it should have been 3x3 since I have 4 entries for the edges, i.e
0-2,
2-4,
4-6

What's going on?

Solution

  • The definition of the edge handle in hist3 is :

     edges{1}(i) <= X(k,1) < edges{1}(i+1)

    So in your case:

     0<= x <2,
 2<= x <4,
 4<= x <6,
 6<= x

    Because it has the <= logic, the last (4th) part of the histogram are for values that exactly equal 6.

    If you dont like it you can just delete the last row \ column of h 

    h(:,end)=[];
h(end,:)=[];