How can I append the content of multiple text file to a new text files based on specific conditions in python?

Question

I have text files that are named in the following way:

• 301_1.txt
• 301_2.txt
• 301_3.txt

I would like to create a new file with all the content of the files that have the same number before the "_". In this instance, the new file should be 301.txt. What is the best way to do this in Python?

Thank you

Answer 1

This is my approach: (hope it helps :) )

Firstly, we need to store the files starting with "301":

import os
files = []
directory = os.fsencode(directory of files)

for file in os.listdir(directory):
    filename = os.fsdecode(file)

    if filename.startswith("301"): 
        files.append(filename)

The directory of files is the directory of where your files go.

Now we need to fetch the data from the files:

data = []
for f in files:
    with open(f) as file:
        for i,row in enumerate(file):
          data.append(row)

Finally we need to write the "301.txt" file:

with open("301.txt",'w') as newfile:
    for row in data:
        newfile.write(row)

Answer 2

You could so something like this.

# populated by os.listdir or something
FILES = ['301_1.txt', '301_2.txt', '301_3.txt', '302_1.txt', '302_2.txt']


def concat_files(base='301'):
    with open(base + '.txt', 'a+') as basefile:
        for file in [f for f in FILES if f.startswith(base + '_')]:
            with open(file) as content:
                basefile.write(content.read())


concat_files(base='301')

Answer 3

import glob
import os
pwd=os.getcwd()
os.chdir('path_to_your_directory')
for i in glob.glob('*.txt'):
    new_name=i.split('_')[0]    #fetch the name before '_'
    write_file=open(new_name+'.txt','a')  #open file in append mode
    read_file=open(i)
    lines=read_file.read()
    write_file.write(lines)
    write_file.close()
    read_file.close()      #close the files

os.chdir(pwd)            

glob.glob('*.txt') will return a list of all files with extension .txt in the current directory. First, we store the present directory in pwd , then to get to the current directory we use os.chdir() from os module and at last, we return to our starting directory by os.chdir(pwd) . If you don't want newline characters then use read_file.read().rstrip() instead.