Is there a way to change the variable used in a function while in a for loop?

Question

I'm taking computer science courses at my school I need to figure out some code for an exam, I need to change the variable name after I print it in a for-loop after decoding RLE. It's hard for me to explain but I hope you understand.

I've tried to look it up online but I can't find the proper way to phrase the problem I have.

import re

def decode(string):
    return re.sub(r'(\d+)(\D)', lambda m: int(m.group(1)) * m.group(2), string)

ch=int(input())

for x in range(0, ch):
    globals()['line%s' % x]=input()

for x in range(0, ch):
    print(decode(['line%s' % x]))

The result I'm looking for is after entering the RLE line by line (ch is the amount of lines), the function I made takes the variable names created by the for loop (so their names are line0, line1, line2 etc... until line(ch)) and then proceeds to decompress and print the RLE but I cant seem to get it to work

Edit: I might have made my problem not obvious and I apologize, I want to fix the last two lines of code so that the RLE is decompressed and printed in one for loop, I don't know if this is possible but I just want to know how (if) I can somehow make print(decode(['line%s' % x])) work, so like the variable line followed by a number gets changed while in the variable. Sorry I'm terrible at explaining things.

Why adding to globals? Add inputs into a list, loop over list and feed data to decode - this looks abusive - poor python. — Patrick Artner
– Patrick Artner, Commented May 1, 2019 at 20:37
@J decoding RLE : "5e" -> "eeeee" - some kind of reverse run length decoder — Patrick Artner
– Patrick Artner, Commented May 1, 2019 at 20:40
Any time you find yourself creating variables with sequential names like line0, line1, line2, etc. you should just use a list. Other dynamic variable names should be dictionaries. — Barmar
– Barmar, Commented May 1, 2019 at 20:42
Seriously, sequentially named variables are a bad idea. Use a list so you can simply refer to line[0], line[1], ... line[x]. — Blorgbeard
– Blorgbeard, Commented May 1, 2019 at 20:50

chepner · Accepted Answer · 2019-05-01 20:51:56Z

5

Creating variable names on the fly is almost always the wrong thing to do. You just need a simple list of values:

lines = []
for x in range(ch):
    lines.append(input())

# or as a list comprehension,
# lines = [input() for x in range(ch)]

for x in lines:
    print(decode(x))

answered May 1, 2019 at 20:51

community wiki

chepner

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1 Comment

Patrikas D Over a year ago

I see the error of my ways now, i was horrifically over complicating things and should have just gone with the simple solution. Thank you so much @chepner !!!!

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