How do I get python to read only every other line from a file that contains a poem

问题

I know the code for reading every line is

f=open ('poem.txt','r')
for line in f: 
    print line 

how do you have python read only even-numbered lines from the original file. Assuming 1-based numbering of lines.

回答1:

There are quite a few different ways, here a simple one

with open('poem.txt', 'r') as f:
    count = 0
    for line in f:
        count+=1
        if count % 2 == 0: #this is the remainder operator
            print(line)

This also might be a little nicer, saving the lines for declaring and incrementing the count:

with open('poem.txt', 'r') as f:
    for count, line in enumerate(f, start=1):
        if count % 2 == 0:
            print(line)

回答2:

From Nick Bastin's comment:

with open('poem.txt', 'r') as f:
    for count, line in enumerate(f, start=1):
        if count % 2 == 0:
            print line

来源：https://stackoverflow.com/questions/30551945/how-do-i-get-python-to-read-only-every-other-line-from-a-file-that-contains-a-po