Replace value from text in python

Question

I’ve the following line in my file test.sdl:

PHASE 1: [Walk_Towards] [-, 1 to 3, -3 to -5][Ego:-4 to -2, FSL]

I want to replace the 1 to 3 with new random numbers (x,y) like 4 to 11. This two numbers are not fixed and generated by a random method and changing for every iteration.

Note the 1 to 3 also not fixed and it is varied for every file

all the files have the same structure Like

PHASE 1: [] [, to ,  to ][Ego: to , FSL]

So I would like to change only the numbers in between the first ‘to‘

My ultimate goal is to do an iteration lets say of 6. For every iterate the numbers will change

for example :

The current line is : PHASE 1: [Walk_Towards] [-, 1 to 3, -3 to -5][Ego:-4 to -2, FSL]

Second iteration will be based on a pre-defined variables (x,y) that changes every time randomly. So the result will be

`PHASE 1: [Walk_Towards] [-, x2 to y3, -3 to -5][Ego:-4 to -2, FSL]`

Third : PHASE 1: [Walk_Towards] [-, x2 to y3, -3 to -5][Ego:-4 to -2, FSL]

And so

This is the only numbers that i need to replace in the file. The format of the PHASE 1 is standard the only values change are numbers
I used:

for line in lines:
        if 'PHASE 1:' in line:
            print(line)
            print(line.split('[')[2].split(','))

I could manage to get the following data:
[‘-‘, ‘ 1 to 3’, ‘ -3 to -5]’]

But I could not go beyond that How can take these values and replace them with my own and change the file for that. Any help would be appreciated

Asked By: user19640240

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Source

Answer 1

This is where a regular expression might come in handy. Using re.sub, you could do

re.sub(r'(?P<start>[.+?,s*)d+s+tos+d+s*,', f'g<start>{n1} to {n2},', line)

with n1 and n2 the randomly generated substitution values.

To explain that a bit more, here’s a fuller code sample, with the verbose flag turned on and comments to explain the regular expression a bit:

import re

line = "PHASE 1: [Walk_Towards] [-, 1 to 3, -3 to -5][Ego:-4 to -2, FSL]"
n1, n2 = 4, 11

print(re.sub(r'(?P<start>[.+?,s*)d+s+tos+d+s*,', f'g<start>{n1} to {n2},', line))

newline = re.sub(
    r'(?P<start>'     # Capture opening pattern
    '[.+?,s*'       # match: opening bracket + any characters up to a comma + the comma itself + any whitespace
    ')'               # Close capturing group
    'd+s+tos+d+'  # match digit(s) + whitespace + 'to' + whitespace + digit(s)
    's*,',           # match any optional whitespace + the comma

    f'g<start>{n1} to {n2},',  # replacement: opening pattern + "n1 to n2," using an f-string
    line,
    flags=re.VERBOSE
)
print(newline)

which prints

PHASE 1: [Walk_Towards] [-, 4 to 11, -3 to -5][Ego:-4 to -2, FSL]

If the opening pattern is always [-, , it can probably be a bit simpler. But the above also allows for input like ...Towards] [7 to 11, 1 to 3, -3 to -5][... and it will still only replace the middle 1 to 3 only.

Answered By: 9769953

Replace value from text in python

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