Reverse values of elements in list

Question

So I got this list:

my_old_list = [(1,2),(3,4),(5,6),(7,8),(9,0)]

and I would like to reverse the content of the elements to:

my_new_list = [(2,1),(4,3),(6,5),(8,7),(0,9)]

I have find a lot of different things, but it never really changes the list into the way I want.

Since tuples are immutable, there is no way to reverse a tuple in-place. Creating a copy requires more space to hold all of the existing elements. Therefore, this exhausts memory. — zamir, Jan 14 '20 at 20:30

yatu · Answer 1 · 2020-01-14T20:38:30.977

2

Here's one way:

[tuple(reversed(i)) for i in my_old_list]
# [(2, 1), (4, 3), (6, 5), (8, 7), (0, 9)]

Or similarly:

[(*reversed(i),) for i in my_old_list]
# [(2, 1), (4, 3), (6, 5), (8, 7), (0, 9)]

edited Jan 14 '20 at 20:38

answered Jan 14 '20 at 20:33

yatu

score 1 · Answer 2 · answered Jan 14 '20 at 20:33

1

try it :

my_old_list = [(1,2),(3,4),(5,6),(7,8),(9,0)]

for i in range(len(my_old_list)) :
    my_old_list[i] = my_old_list[i][::-1]

print(my_old_list)

answered Jan 14 '20 at 20:33

AmirHmZ

score 0 · Answer 3 · answered Jan 14 '20 at 20:32

0

my_new_list = map(lambda tup: (tup[1], tup[0]), my_old_list)

answered Jan 14 '20 at 20:32

Personman

2

better: `lambda tup: tup[::-1]` to support tuples of any length – DeepSpace Jan 14 '20 at 20:33

score 0 · Answer 4 · answered Jan 14 '20 at 20:32

0

I would use list comprehension here as follows:

new_list = res = [(sub[1], sub[0]) for sub in my_old_list ]

Output

[(2, 1), (4, 3), (6, 5), (8, 7), (0, 9)]

answered Jan 14 '20 at 20:32

Edeki Okoh

1

better: `sub[::-1]` to support tuples of any length – DeepSpace Jan 14 '20 at 20:33

4 Answers4