How to find mean in theta-direction?

I have data store in [x,y,z] format where matrices x [100x100] and y [100x100] store the coordinates and matrix z [100x100] is the value I would like to average. Basically, I would like to create a 1D distribution of z in r-direction. However, I am not sure how to perform averaging in the theta-direction. Any help would be greatly appreciated

Answer 1

[Matt J]

[theta,rho]=cart2pol(x,y);

G=discretize(rho,___); %fill in the blank with desired binning specs

zMean=splitapply(@mean,z(:),G(:));

[Patcharawat Charoen-amornkitt]

This is perfect. Thanks a lot!