循环多个文件以根据其名称合并

Question

I'm a new python. I have for loop function gives me a folder contains 100 files "the data inside is numbers and the nuber of raws are the same" like the follow:

A_0.20_1_.txt        for example   A_0.20_1_    B_0.20_1_      
B_0.20_1_.txt                         1            4
A_0.20_2_.txt                         2            5
B_0.20_2_.txt                         3            6

A_0.40_1_.txt
B_0.40_1_.txt
A_0.40_2_.txt
B_0.40_2_.txt

and so on.....

These files saved in a folder named output I need to merge the two files form the output folder into one file like:

merged_A_B_0.20_1_.txt       for example   merged_A_B_0.20_1_
merged_A_B_0.20_2_.txt                        1    4
                                              2    5
merged_A_B_0.40_1_.txt                        3    6
merged_A_B_0.40_2_.txt

and so on.....

I tried to use the following code:

filename_list = [f for f in os.listdir(r'C:\Users\output\')if os.path.isfile(f)] 
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) 

But it doesn't work and give me error

     Traceback (most recent call last):

File "<ipython-input-6-5df3067f04e7>", line 1, in <module>
runfile('C:/Users/user/Downloads/combine 2 files new2.py', wdir='C:/Users/user/Downloads')

File "C:\ProgramData\Anaconda3\lib\site-
 packages\spyder\utils\site\sitecustomize.py", line 866, in runfile
execfile(filename, namespace)

File "C:\ProgramData\Anaconda3\lib\site-
  packages\spyder\utils\site\sitecustomize.py", line 102, in execfile
exec(compile(f.read(), filename, 'exec'), namespace)

File "C:/Users/user/Downloads/combine 2 files new2.py", line 22, in 
<module> columns = np.vstack(columns).T

File "C:\ProgramData\Anaconda3\lib\site-
packages\numpy\core\shape_base.py", line 230, in vstack
return _nx.concatenate([atleast_2d(_m) for _m in tup], 0)

ValueError: need at least one array to concatenate    

Please, any help?

Answer 1

Your code is actually working the problem is you don't pass a full path to os.path.isfile() so it does not return True and your list of files is empty

import numpy as np
import os
file_path = r"C:\Users\output"
filename_list = []
for file in os.listdir(file_path):
    file = os.path.join(file_path, file)
    if os.path.isfile(file):
        filename_list.append(file)

columns = []
for filename in filename_list:
    with open(filename, 'r') as f:
        x = np.array([float(raw) for raw in f.readlines()])
        columns.append(x)
columns = np.vstack(columns).T
np.savetxt('filename_out.txt', columns)

This writes the data of all files into ONE file with one column for each file