如何在python中逐行读取文件并逐元素读取列表元素

Question

I have a text file and a list of integers in python. I want to read the contents of the file line by line whereas parse the elements of the list simultaneous.

Here is an example of contents of the text file (myfile.txt):

line1
line2
line3

and the list is:

mylist = (1, 2, 3)

for example, I want to have a loop like below:

for line, item in open(myfile.txt), mylist:
  print line
  print item

and I expect to see this output:

line1
1
line2
2
line3
3

Answer 1

Use zip :

for line, item in zip (open ('myfile.txt'), mylist):
  print (line)
  print (item)

the loop will stop when the shortest of the iterables is exhausted.

Answer 2

If you don't want to read the whole file in one go you could use itertools.izip if you using python2:

for line, item in itertools.izip(open("myfile.txt", mylist)):
    print(line)
    print(item)

If you're using python3 you should use zip instead:

for line, item in zip(open("myfile.txt", mylist)):
    print(line)
    print(item)

If you don't mind reading the file in one go you could use zip anyway (both for python2 and 3).