Extracting specific columns in numpy array

Question

This is an easy question but say I have an MxN matrix. All I want to do is extract specific columns and store them in another numpy array but I get invalid syntax errors. He

Answer 1

One more thing you should pay attention to when selecting columns from N-D array using a list like this:

data[:,:,[1,9]]

If you are removing a dimension (by selecting only one row, for example), the resulting array will be (for some reason) permuted. So:

print data.shape            # gives [10,20,30]
selection = data[1,:,[1,9]]
print selection.shape       # gives [2,20] instead of [20,2]!!