I have a three-dimensional array, and I'd like to be able to find a specific value and get the three coordinates.
For example, if I have:
A = [2 4 6; 8 10 12]
A(:,:,2) = [5 7 9; 11 13 15]
and I want to find where 7 is, I'd like to get the coordinates i = 1 j = 2 k = 2
I've tried variations of find(A == 7), but I haven't got anywhere yet.
Thanks!
The function you seek is ind2sub:
[i,j,k]=ind2sub(size(A), find(A==7))
i =
1
j =
2
k =
2
You can use find to locate nonzero elements in an array, but it requires a little bit of arithmetic. From the documentation:
[row,col] = find(X, ...)returns the row and column indices of the nonzero entries in the matrix X. This syntax is especially useful when working with sparse matrices. If X is an N-dimensional array with N > 2, col contains linear indices for the columns. For example, for a 5-by-7-by-3 array X with a nonzero element at X(4,2,3), find returns 4 in row and 16 in col. That is, (7 columns in page 1) + (7 columns in page 2) + (2 columns in page 3) = 16.
If the matrix M has dimensions a x b x c, then the indices (i,j,k) for some value x are:
[row,col] = find(A==x);
i = row;
j = mod(col,b);
k = ceil(col/b);
