如何获取文本文件并创建带有编号行的副本

Question

This poem is saved in a text file:

'Twas brillig, and the slithy toves
   Did gyre and gimble in the wabe;
All mimsy were the borogroves,
   And the mom raths outgrabe.
               - Lewis Carroll

I want to create a copy of that file and change the name and have the output look like this:

1: 'Twas brillig, and the slithy toves
2:   Did gyre and gimble in the wabe;
3: All mimsy were the borogroves,
4:   And the mom raths outgrabe.
5:             - Lewis Carroll

Can this be done using a loop or is there a simpler way to do this?

Answer 1

You can iterate through each line of the poem file and get the line number using enumerate :

with open('poem.txt') as poem_file:
    with open('poem-numbered.txt', 'w') as numbered_file:
        for index, line in enumerate(poem_file, 1):
            numbered_file.write('{}: {}'.format(index, line))

The code above first opens the original poem file ( poem.txt ) and then opens a file for writing to it (hence the w as the second argument to open ). It then iterates through the lines of the original file and writes the line to the output file ( poem-numbered.txt ) with the line number.

When passing w as the second argument to open , if the file already exists, it will be overwritten and if it doesn't exist, it will be created.