Reverse only numbers from file

Question

How can I reverse only number and not the text from this ?

datas.txt

Bungo Charlie
Bungo Echo
Bungo Bravo
Bungo Tango
Bungo Alpha

with open('datas.txt', 'r') as f:
    for i, line in enumerate(f):
        print('{}. {}'.format(i+1, line.strip()))

Expectation:

5. Bungo Charlie
4. Bungo Echo
3. Bungo Bravo
2. Bungo Tango
1. Bungo Alpha

What I got :

1. Bungo Charlie
2. Bungo Echo
3. Bungo Bravo
4. Bungo Tango
5. Bungo Alpha

Answer 1

Simply using the reversed() function will reverse everything:

for i, line in reversed(list(enumerate(f))

If you'd like to only reverse the numbers, you can do it selectively (but messily) like so:

reversed(list(enumerate(reversed(f))))

If you want something cleaner, you can define a function using zip():

def reverse_enumerate(x):
    return zip(reversed(range(len(x))), reversed(x))