将多个文本文件合并为一个文本文件？

Question

I'm trying to combine multiple files into one, where each of them contains one column and I need to get one file with two columns and plot the resulted file like (x,y) as follows:

x       y       result
1       4       1   4
2       5       2   5
3       6       3   6

and run the code for n text files.

How can I do this?

Answer 1

here's a quick-and-dirty solution. I assumed that all files have the exact number of rows. The function write_files gets an input files which is a list of file-paths (strings).

def write_files(files):
    opened_files = []
    for f in files:
        opened_files.append(open(f, "r"))

    output_file = open("output.txt", "w")
    num_lines = sum(1 for line in opened_files[0])
    opened_files[0].seek(0,0)
    for i in range(num_lines):
        line = [of.readline().rstrip() for of in opened_files]
        line = " ".join(line)
        line += "\n"
        output_file.write(line)
    for of in opened_files:
        of.close()
    output_file.close()

write_files(["1.txt", "2.txt"])

Answer 2

A simple solution assuming that all files have the same number of elements in float format.

import numpy as np
filename_list=['file0.txt', 'file1.txt']#and so on
columns = []
for filename in filename_list:
    f=open(filename)
    x = np.array([float(raw) for raw in f.readlines()])
    columns.append(x)
columns = np.vstack(columns).T
np.savetxt('filename_out.txt', columns)

see also the method savetxt to customize the output

EDIT: if you have 100 files in a certain directory (let's call it files_dir ) you can use the method listdir in the os library, be be careful, since listdir returns directories and files:

import os
filename_list = [f for f in os.listdir(files_dir) if os.path.isfile(f)]