Reading two text files line by line simultaneously
Python does let you read line by line, and it's even the default behaviour - you just iterate over the file like would iterate over a list.
wrt/ iterating over two iterables at once, itertools.izip is your friend:
from itertools import izip
fileA = open("/path/to/file1")
fileB = open("/path/to/file2")
for lineA, lineB in izip(fileA, fileB):
print "%s\t%s" % (lineA.rstrip(), lineB.rstrip())
from itertools import izip
with open("textfile1") as textfile1, open("textfile2") as textfile2:
for x, y in izip(textfile1, textfile2):
x = x.strip()
y = y.strip()
print("{0}\t{1}".format(x, y))
In Python 3, replace itertools.izip
with the built-in zip
.
with open(file1) as f1, open(fil2) as f2:
for x, y in zip(f1, f2):
print("{0}\t{1}".format(x.strip(), y.strip()))
output:
This is a the first line in English C'est la première ligne en Français
This is a the 2nd line in English C'est la deuxième ligne en Français
This is a the third line in English C'est la troisième ligne en Français
We could use generator
for more convenient file opening, and it could easily support to iterator on more files simultaneously.
filenames = ['textfile1', 'textfile2']
def gen_line(filename):
with open(filename) as f:
for line in f:
yield line.strip()
gens = [gen_line(n) for n in filenames]
for file1_line, file2_line in zip(*gens):
print("\t".join([file1_line, file2_line]))
Note:
- This is
python 3
code. Forpython 2
, useitertools.izip
like other people said. zip
would stop after the shortest file is iterated over, useitertools.zip_longest
if it matters.