How to fill numpy array by row and column

Question

I want to fill the first and the last row and the first and the last column of a grid with 4.

Input:

grid = np.zeros((5, 5))
[[   0.   0.   0.   0.   0. ]
 [   0.   0.   0.   0.   0. ]
 [   0.   0.   0.   0.   0. ]
 [   0.   0.   0.   0.   0. ]
 [   0.   0.   0.   0.   0. ]]

output:

[[   4.   4.   4.   4.   4. ]
 [   4.   0.   0.   0.   4. ]
 [   4.   0.   0.   0.   4. ]
 [   4.   0.   0.   0.   4. ]
 [   4.   4.   4.   4.   4. ]]

I tried to do this with a for loop but is there a better option than that?

nisemonoxide · Accepted Answer · 2018-02-17 14:52:20Z

2

To change the values of first and last rows:

grid[[0,-1],:] = 4

To change the values of first and last columns:

grid[:, [0,-1]] = 4

edited Feb 17, 2018 at 14:52

answered Feb 17, 2018 at 14:47

nisemonoxide

4512 silver badges7 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

How to fill numpy array by row and column

1 Answer 1

Comments

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Related