Python将某些行从一个文件复制到另一个文件

Question

I want to copy specific lines from one file to another.

I can copy the entire file quite easily with:

or_profile_file = open('or_profile.prof')
new_profile_file = open('new_profile.prof','w')

for line in or_profile_file:
    new_profile_file.write(line)

or_profile_file.close()
new_profile_file.close()

How can I copy only specific lines though? In this case I want to copy only the first 109 lines, but would also be interested in knowing how to copy different specific lines, for instance copying lines 1,5,38 and 200?

Answer 1

Use enumerate to get the line number while iterating over the file:

desired_lines = [1, 5, 38, 200]

for n, line in enumerate(or_profile_file):
    if (n+1) in desired_lines:
        new_profile_file.write(line)

Note that n starts at zero, I assume you are counting from 1, that is why I test for (n+1).

Answer 2

You can use enumerate to find out line numbers and write them accordingly:

or_profile_file = open('or_profile.prof')
new_profile_file = open('new_profile.prof','w')

lines_to_write = [1, 5, 38, 200]

for linenum, line in enumerate(or_profile_file):
    if linenum+1 in lines_to_write:
        new_profile_file.write(line)

or_profile_file.close()
new_profile_file.close()

Do note that line numbers start from 0. That's why it's linenum+1