Q:

Map over slices

Julia's map and comprehension syntax make it easy to map over all elements of a multidimensional array.
Is there a similar support for mapping over slices of an array? 
As a silly example, given a 3x3x100 matrix, I might want to map over all 100 3x3x_ slices. I might, say, derive the determinant of each 3x3 slice, and end up with a 1x1x100 array of determinants.

A:

Look at mapslices. For the question suggest an example with size(A)==(3,3,100). Calculating the 100 determinantst of 3x3 matrices can be done with: mapslices(det,A,(1,2)).
Note the resulting matrix is still 3 dimensional, and squeeze can be used to get rid of the size 1 dimensions. In the example:
squeeze(mapslices(det,A,(1,2)),(1,2))

