MATLAB: get index of minima in 3D array

Question

i have a little question about MATLAB.

I have a 3D-array where each 2D-layer is a picture. What i need is the "third" index (=the number of the layer) of the lowest value for each pixel in this array. At the end i want to have a 2D array where i have the index of these lowest values.

An example:

3D array with these 2 2D-layers:

layer 1:

3-5-6
1-4-2
7-5-2

layer 2:

1-8-2 
4-6-1 
9-2-5

The result should be the following array:

2-1-2
1-1-2
1-2-1

I hope you can see what i want to achieve, sorry for my bad English, I cannot really express my problem in words...

Thank you for your help.

Answer 1

Let A be the matrix then you can use

[B, I] = min(A, [], 3);

Where B is the minimum values and I contains the indices. If you are not interested in minimum values you can use

[~, I] = min(A, [], 3);

For you example

>> A(:,:,1) = [3 5 6; 1 4 2; 7 5 2];
>> A(:,:,2) = [1 8 2; 4 6 1; 9 2 5];
>> [B,I]=min(A, [], 3)
B =
     1     5     2
     1     4     1
     7     2     2
I =
     2     1     2
     1     1     2
     1     2     1