CODEWITHSUNDEEP
pythonreplace
Jinxsica
Jinxsica

Reputation: 1

how to search and replace for multiple value of text file in python?

My data:

1 255 59 0 1 255 0 1 1 0 4 0 5 

0 1 255 1 253 0 90 1 1 0 2 0 233

I'm new to python and I need to replace all value in text file by use conditions:

  1. If value in line = 255, Replace as 1

  2. If value in line < 255 (254, 253, 252...), Replace as 0

So, My target data is:

1 1 0 0 1 1 0 1 1 0 0 0 0 

0 1 1 1 0 0 0 1 1 0 0 0 0

How can I solve this problem?

Actually, I tried to fix it but doesn't work with my data.

This is my code:

f1 = open('20130103.txt','r')
f2 = open('20130103_2.txt','w')
count = 255
for line in f1:
    line = line.replace('255','1')
    count = count-1
    line = line.replace('%d'%(count), '0')
    f2.write(line)
f1.close()
f2.close()

And result is:

1 1 59 0 1 1 0 1 1 0 4 0 5 
0 1 1 1 0 0 90 1 1 0 2 0 233

Upvotes: 0

Views: 359

Answers (3)

Abhijit
Abhijit

Reputation: 63777

The eye catcher here is the number 255, for which you would want to display 1, which clearly indicates, you are only interested in the 8th bit. The only case which looks strange is how your o/p not conforming with your requirement, does not manipulate 1 in which case, you have to leave it out of your transformation

If I have to trust your requirement

>>> with open("test.in") as fin, open("test.out","w") as fout:
    for line in fin:
        line = (e >> 7 for e in map(int, line.split()))
        fout.write(''.join(map(str, line)))
        fout.write('\n')

If I have to trust your data

>>> with open("test.in") as fin, open("test.out","w") as fout:
    for line in fin:
        line = (e >> 7 if e != 1  else 1 for e in map(int, line.split()))
        fout.write(''.join(map(str, line)))
        fout.write('\n')

Another alternate view to this problem.

>>> with open("test.in") as fin, open("test.out","w") as fout:
    for line in fin:
        line = (e / 255 if e != 1  else 1 for e in map(int, line.split()))
        fout.write(''.join(map(str, line)))
        fout.write('\n')

Upvotes: 2

Blender
Blender

Reputation: 298552

You could do something like this:

with open('20130103.txt', 'r') as f1, open('20130103_2.txt', 'w') as f2:
    for line in f1:
        values = line.split()
        new_values = ' '.join('1' if value == '255' else '0' for value in values)

        f2.write(new_values + '\n')
  • line.split() splits the line into chunks. 'a b'.split() == ['a', 'b']
  • '1' if value == '255' else '0' for value in values is a generator that just outputs '1' or '0', depending on the value of an item in your list of values.
  • ' '.join() joins together the values in the list (or generator, in this case) with a space.

Upvotes: 1

alan
alan

Reputation: 4852

Here's an example of how you can pass re.sub a function -- instead of a replace string -- to gain really fine control over how replacements are done:

import re
lines = ['1 255 59 0 1 255 0 1 1 0 4 0 5',
     '0 1 255 1 253 0 90 1 1 0 2 0 233']
def do_replace(match):
    number = int(match.group(0))
    if number == 0 or number == 1:
        return str(number)
    elif number == 255:
        return '1'
    elif number < 255:
        return '0'
    else:
        raise ValueError
for line in lines:
    print re.sub(r'\d+', do_replace, line)

prints:

1 1 0 0 1 1 0 1 1 0 0 0 0
0 1 1 1 0 0 0 1 1 0 0 0 0

Upvotes: 1

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