Concatenate multiple files into a single file object without creating a new file

Question

This question is related to Python concatenate text files

I have a list of file_names, like [\'file1.txt\', \'file2.txt\', ...].

I wou

Answer 1

You can use fileinput package. This module implements a helper class and functions to quickly write a loop over a list of files

import fileinput
with fileinput.input(files=('file1.txt', 'file2.txt', 'file3.txt')) as f:
    for line in f:
      #rest code

Answer 2

Simplest way, is to use itertools.chain,

which provide an easy way to read from multiple iterators.

Make an iterator that returns elements from the first iterable until it is exhausted, then proceeds to the next iterable, until all of the iterables are exhausted. Used for treating consecutive sequences as a single sequence.

Let's assume you have to files: file1.txt and file2.txt.

file1.txt data is:

file1 line1
file1 line2

and, the same way, file2.txt data is:

file2 line1
file2 line2

This code:

 for f in chain(map(open, ['file1.txt', 'file2.txt'])):
     for line in f:
         print(line.strip())

will output this:

file1 line1
file1 line2
file2 line1
file2 line2