List comprehension to append an element to a tuple

Question

I have a numpy array

arr = np.array([
        [1, (10, 20, 30, 40)],
        [2, (10, 20, 30, 40)],
        [5, (11, 22, 33, 44)]
      ])

I wonder if there's a way that I can get :

ans = [
        [1, 10, 20, 30, 40],
        [2, 10, 20, 30, 40],
        [5, 11, 22, 33, 44]
      ]

using list comprehension in python.

I've tried:

ans = [list(row[1]).append(row[0]) for row in arr]

but got [None, None, None] as the output

That's not a numpy array, so your question is moot. Please provide code that matches your prose. — Mad Physicist, Jul 19 '21 at 16:20
`append` would put `1`, `2`, and `5` at the *end* of the respective lists anyway, not at the beginning. — chepner, Jul 19 '21 at 16:22

score 0 · Accepted Answer · answered Jul 19 '21 at 16:21

0

append returns None, not the list being appended to. (Also, append would insert the item at the wrong end anyway.)

ans = [[x, *y] for x, y in arr]

answered Jul 19 '21 at 16:21

chepner

1 Answers1