Replacing commas with dots and save the change, doesn't work good with me?

Question

I have 10 files, each one of them has 2 columns with 1000000 rows. I'm trying to replace all comma's in my files with dots. I used the following script

import glob
import os, os.path

list =[]
for filename in glob.glob("inputfile/*"):
    with open(filename, 'r') as searchfile:
        for line in searchfile:
            if ',' in line:
                replace=line.replace(",", ".")
                list.append(replace)
                f = open(filename, 'w')
                for item in list:
                    f.write(item)

It's working, but the resulted files have 2 columns and just 365 rows, which means that I lost 999635 rows of my data.

can you help me please??

 Edit:

 sample of my data
-0,0222950  0,1429029
-0,0216510  0,1419368
-0,0226171  0,1406487
-0,0222950  0,1393607

Maybe is cause other lines doesnt contains "," ?? (if ',' in line:) — Wonka, Oct 30 '19 at 09:50
Possible duplicate of [How to search and replace text in a file?](https://stackoverflow.com/questions/17140886/how-to-search-and-replace-text-in-a-file) — alex, Oct 30 '19 at 09:52
You close and replace the file-for-writing *for each line* of the file-for-reading. — MisterMiyagi, Oct 30 '19 at 09:52
You can try yield. See the next post: https://stackoverflow.com/questions/519633/lazy-method-for-reading-big-file-in-python — Tsvetelina Mariyanova, Oct 30 '19 at 09:57
@Cashoo ok so i think the problem is you are opening file each time on loop and dont close when write. Acumulate result in list and write it only one time at end out of loops. MisterMiyagi posted it — Wonka, Oct 30 '19 at 10:07
@KarthickMohanraj I added it, please check my question again! — Cashoo, Oct 30 '19 at 10:07

Rakesh · Accepted Answer · 2019-10-30T10:17:09.490

This is one approach. Write to a temp file and after processing rename the temp file to original file and delete old file

Ex:

import glob
import os, os.path

base_path = "inputfile/"
for filename in glob.glob("{}\*".format(base_path)):
    path, file_name = os.path.split(filename)
    with open(filename, 'r') as searchfile, open(os.path.join(path, "temp_{}".format(file_name)), 'w') as searchfile_out:
        for line in searchfile:
            if ',' in line:
                line = line.replace(",", ".")
            searchfile_out.write(line)   #Write to temp file

    os.rename(filename, os.path.join(path, "OLD_{}".format(file_name)))    #Rename old file
    os.rename(os.path.join(path, "temp_{}".format(file_name)), filename)  #Rename temp file to original file

Replacing commas with dots and save the change, doesn't work good with me?

1 Answers1