How to change entire row/column to the same value in a matrix-CodePudding

So I have this 3d array

x = np.zeros((9, 9))

Output:

[[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 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 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 0 0 0 0 0 0]]

and I want to change all of row x and column y into 1

Desired output:

[[0 0 0 0 0 1 0 0 0]
 [0 0 0 0 0 1 0 0 0]
 [0 0 0 0 0 1 0 0 0]
 [1 1 1 1 1 1 1 1 1]
 [0 0 0 0 0 1 0 0 0]
 [0 0 0 0 0 1 0 0 0]
 [0 0 0 0 0 1 0 0 0]
 [0 0 0 0 0 1 0 0 0]
 [0 0 0 0 0 1 0 0 0]]

I am doing this on a 3d array with Booleans instead of 0s and 1s but I assume that the answers would be the same.

CodePudding user response：

So first index is for the rows, and second index is for the columns. In your example, if you want to set row n to 1 just do the following:

x[n] = 1

I hope this helps.

CodePudding user response：

Use indexing with broadcasting:

x[n] = 1

# or
x[n,:] = 1