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Python - Write Bytes to File
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Python | Write multiple files data to master file

Last Updated : 06 May, 2019
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Given a number of input files in a source directory, write a Python program to read data from all the files and write it to a single master file. Source directory contains n number of files, and structure is same for all files. The objective of this code is to read all the files one by one and then append the output into a single master file having structure same as source files. Taking three input files as example, named emp_1.txt, emp_2.txt, emp_3.txt, output will contain data from all the input files. 
  Input:           Output:
  Method #1: Using os module Python 
import os # list the files in directory lis = os.listdir('D:\\python'                  '\\data_files\\data_files') print(lis) tgt = os.listdir('D:\\python'                  '\\data_files\\target_file')  file_dir ='D:\\python\\data_files\\data_files' out_file = r'D:\\python\\data_files\\target_file\\master.txt' ct = 0  print('target file :', tgt) try:     # check for if file exists     # if yes delete the file      # otherwise data will be appended to existing file     if len(tgt)>0:         os.remove('D:\\python'                   '\\data_files\\target_file\\master.txt')          open(tgt, 'a').close()     else:         # create an empty file         open(tgt, 'a').close() except:     head = open('D:\\python'                 '\\data_files\\target_file\\master.txt', 'a+')      line ='empno, ename, sal'     # write header to output     print(head, line)     head.close()     # below loop to write data to output file     for line1 in lis:         f_dir = file_dir+'\\'+line1         # open files in read mode         in_file = open(f_dir, 'r+')          # open output in append mode         w = open(out_file, 'a+')         d = in_file.readline()         d = in_file.readlines()         w.write("\n")         for line2 in d:             print(line2)             w.write(line2)                    ct = ct + 1       w.close()
Output:   Method #2: Using pandas Python 
import pandas as pd # pd.read_csv creates dataframes df1 = pd.read_csv('D:\python\data_files\data_files\emp_1.txt') df2 = pd.read_csv('D:\python\data_files\data_files\emp_2.txt') df3 = pd.read_csv('D:\python\data_files\data_files\emp_3.txt')  frames = [df1, df2, df3]  # concat function concatenates the frames  result = pd.concat(frames) # to_csv function writes output to file result.to_csv('D:\\python\\data_files'               '\\target_file\\master.txt', encoding ='utf-8', index = False)
Output:

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Python - Write Bytes to File

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