How do I calculate the mean entry value of multiple 3d matrices, excluding NaN/0?

I have 4 3D matrices of the same size (40x40x22), and I would like to have an matrix 40x40x22 with the mean entries, while excluding 0/NaN values.

I tried doing:

meanMatrix = (Matrix1 + Matrix2 + Matrix3 + Matrix4)/4

which is close, but does not exclude 0/NaN values.

Is there an actual function which allows to do it with 3d matrices? It's not possible to concatenate the 3D matrices (unlike a 2D matrix) and calculate its mean.

Would it be possible to calculate the mean of every entry using a cell array?

Answer 1

[Jan]

If you have your matrices in a cell array instead using indices hidden in the name of the variables, the solution would be easier. But it works:

M           = cat(4, Matrix1 + Matrix2 + Matrix3 + Matrix4);
M(isnan(M)) = 0;
meanM       = sum(M, 4) ./ sum(M ~= 0, 4);

Instead of dividing the sum by the number of matrices, you divide by the number of non-zero elements. The NaNs vanish in the sum, if you replace them by zeros.

You had the right idea already, but stopped too early:

 It's not possible to concatenate the 3D matrices 
 (unlike a 2D matrix) and calculate its mean.

[zhen]

We actually tried the concatenation, but it did not work at first saying that the matrices were of different dimensions, but now it does! Thank you for your help!