How to 'zero' out rows & columns in an array

Question

I have a 2D array to represent a many-many mapping :

0   3   1   3
3   0   0   0
1   0   0   0
3   0   0   0

What is the quickest way to 'zero' out rows and column entries corresponding to a particular index in this array?

Do you really mean a many-many mapping, or is this a 1-1 mapping from pairs of names to numbers? — user2357112, Jul 05 '13 at 07:06
Maybe it's just me, but it's unclear what you are asking. Can you give a more complete example. — root, Jul 05 '13 at 07:12

score 28 · Accepted Answer · answered Jul 05 '13 at 07:07

28

arr[i] = 0   # zeroes out row i
arr[:,i] = 0 # zeroes out column i

answered Jul 05 '13 at 07:07

user2357112

14

perhaps a useful addition: to zero out the whole matrix, use `a[:]=0` – gt6989b Jul 11 '14 at 16:38

1 Answers1