Python process and overwrite external text file

Question

I have a input text file as follows, this is saved as 12.txt:

[(442, 165), (442, 184), (487, 165), (487, 184)],english

My aim is to remove all the special characters from this file and overwrite it : I am using below python script :

import os
import numpy as np
import math
import cv2 as cv

#path = '/media/D/code/OCR/text-detection-ctpn/data/mlt_english+chinese/image'
gt_file = '12.txt'

with open(gt_file, 'r+') as f:
    for line in f.readlines():
        line = line.replace("[", "")
        line = line.replace("(", "")
        line = line.replace(")", "")
        line = line.replace("]", "")
        line = line.replace(" ", "")

        f.write(line)

However it gives me this output:

[(234, 162), (234, 183), (307, 162), (307, 183)],english
234,162,234,183,307,162,307,183,english

I dont want the output to be appended as it is as shows above I want the output to overwrite 12.txt. Filethat is 12.txt after running python script should look like this:

234,162,234,183,307,162,307,183,english

I have referred Python replace and overwrite instead of appending but there is some thing I am missing

Does using 'w+' instead of 'r+'as an option when opening the file not work? — TUI lover, Aug 09 '19 at 11:14
@TUIlover `w+` truncates the file, so OP will not be able to read the data. — kabanus, Aug 09 '19 at 11:20

score 2 · Accepted Answer · edited Aug 09 '19 at 11:20

You need to open temp file and read from file, remove old file and rename to new name

import os
import numpy as np
import math
import cv2 as cv

#path = '/media/D/code/OCR/text-detection-ctpn/data/mlt_english+chinese/image'
gt_file = '12.txt'
output = open("temp.txt","w")
with open(gt_file, 'r') as f:
    for line in f:
        line = line.replace("[", "")
        line = line.replace("(", "")
        line = line.replace(")", "")
        line = line.replace("]", "")
        line = line.replace(" ", "")

        output.write(line)
output.close()
os.remove(gt_file) # remove old file
os.rename("temp.txt",gt_file) # rename as old file

score 2 · Answer 2 · answered Aug 09 '19 at 11:14

Separate the two processes, it's way cleaner.

#read and edit lines
to_write = [] #store edited lines
with open(gt_file, 'r') as f:
    for line in f.readlines():
        ...
        to_write.append(line)

#write back edited lines
with open(gt_file, 'w') as f:
    for line in to_write:
        f.write(line)

score 0 · Answer 3 · answered Aug 09 '19 at 11:20

The reason is, you file pointer has reached the end. Given a single line in text file, seek() and truncate() functions can be used to reproduce the results that you require.

import os
import numpy as np
import math

gt_file = '12.txt'

with open(gt_file, 'r+') as f:
    for line in f.readlines():
        line = line.replace("[", "")
        line = line.replace("(", "")
        line = line.replace(")", "")
        line = line.replace("]", "")
        line = line.replace(" ", "")
        f.seek(0)
        f.truncate()
        f.write(line)

score 0 · Answer 4 · answered Aug 09 '19 at 11:21

I used this

file = open('test_file', 'r')
data = file.read()
file.close()

data = data.replace("[", "")
data = data.replace("(", "")
data = data.replace(")", "")
data = data.replace("]", "")
data = data.replace(" ", "")
print(data, file=open('test', 'w'))

Check if this works for you.

Python process and overwrite external text file

4 Answers4