Extracting column vectors from matrix.
Say that I have a rank2 array (matrix) of shape (m,n). Call it A.
When extracting column vectors from A, I often want to keep the result as a rank2 column vector (for subsequent matrix multiplications, etc), so I usually end up writing something ugly like this:
column_vector = reshape(A[:,col],(m,1))
I've got a function to wrap this, but is there a builtin (or cleaner) way to do this sort of operation?
TIA.
Andrew.
On Thursday 04 September 2003 11:58, Andrew Nesbit wrote:
Say that I have a rank2 array (matrix) of shape (m,n). Call it A.
When extracting column vectors from A, I often want to keep the result as a rank2 column vector (for subsequent matrix multiplications, etc), so I usually end up writing something ugly like this:
column_vector = reshape(A[:,col],(m,1))
I've got a function to wrap this, but is there a builtin (or cleaner) way to do this sort of operation?
1) A[:, col:col+1]
or perhaps
2) A[:, col][:, NewAxis]
Konrad.
Konrad Hinsen hinsen@cnrsorleans.fr writes:
 A[:, col:col+1]
or perhaps
 A[:, col][:, NewAxis]
Yep, those are the sort of tricks I was looking for. Thankyou.
Andrew.
participants (2)

Andrew Nesbit

Konrad Hinsen