editing a single element in text file in python

Question

I have 500 *.txt files which are of the form given below

1 0.211648 0.496528 0.230114 0.159722
11 0.549716 0.232639 0.082386 0.145833
5 0.687500 0.539931 0.130682 0.128472
1 0.534091 0.809028 0.221591 0.194444
2 0.127841 0.637153 0.119318 0.128472
2 0.579545 0.482639 0.090909 0.069444
1 0.657670 0.269097 0.105114 0.121528
2 0.737216 0.348958 0.025568 0.086806
2 0.484375 0.302083 0.031250 0.069444

I need to replace '11' 1st number in the row with '10' I have written following program for it but it doesn't work. can you please help.

import numpy as np
import glob
import os

os.chdir(r'../images')
myFiles = glob.glob('image*.txt')
import numpy as np
for i1 in myFiles:

  # print(i1)
  with open(i1, 'r') as f:
    # read a list of lines into data
    lines = f.readlines()

  r_id = np.arange(len(lines))
  for i in r_id:
      idx = list(map(float, lines[i].split(' ')))
      idx[0]=int(idx[0])
      if(idx[0]==11): 
        idx[0]=10
        with open(i1, 'w') as f:
          f.writelines(lines)

  f.close()

perhaps you meant myFiles = glob.glob('image\*.txt')?

user15801675
– user15801675

2021-05-28 16:46:36 +00:00
Commented May 28, 2021 at 16:46 — user15801675
– user15801675, Commented May 28, 2021 at 16:46
@Sujay I checked by printing the file names

anfjnlnl
– anfjnlnl

2021-05-28 16:56:14 +00:00
Commented May 28, 2021 at 16:56 — anfjnlnl
– anfjnlnl, Commented May 28, 2021 at 16:56

Tim Roberts · Accepted Answer · 2021-05-28 17:07:57Z

2

You're trying to use integers (10 and 11), but what you have there are strings. You don't need numpy for this, it's a simple text substitution:

import glob
import os

os.chdir('../images')
myFiles = glob.glob('image*.txt')
for i1 in myFiles:
    lines = open(il,'r').readlines()
    with open(il,'w') as fout:
        for line in lines:
            if line.startswith('11 '):
                line = '10 '+line[3:]
            print( line, file=fout, end='' )

It could be even simpler if you wanted to write the result to a temp file and rename afterward. Then you wouldn't need to read the whole file in.

edited May 28, 2021 at 17:07

answered May 28, 2021 at 16:50

Tim Roberts

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2 Comments

anfjnlnl Over a year ago

your code creates spaces between lines, can you please tell me how to fix that

Tim Roberts Over a year ago

Honestly, you should have been able to figure that out. It has spaces because "readlines" leaves the newline at the end, and print adds another. So, you can either .strip() the newline, or tell print not to add one, which is what I did here.

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