How to remove characters from the end or start of every element in a Python list

Question

I need help removing characters from the start and end of every element in a Python list.
For instance,

list = ["ab1c", "ef2g", "hi3j"]

If this was the list and I wanted to remove the letters from each element by removing the first two and the last character so that the end result would be list = [1, 2, 3], how could I do this?

Asked By: Arvo Ju

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Source

Answer 1

Use re.sub to strip the first two chars and the last one char from the string. Here, . is any character, .* is any character repeated 0 or more times, \1 is the first capture group, that is, whatever was matched inside the parentheses.

import re
lst = ["ab1c", "ef2g", "hi3j"]
lst = [int(re.sub(r'..(.*).', '\1', s)) for s in lst]
print(lst)
# [1, 2, 3]

Answered By: Timur Shtatland

Answer 2

You can try using the .strip() method in python. This would work independent of how many characters are before or after the digit in each string.

import string

list = ["ab1c", "ef2g", "hi3j"]
list = [word.strip(string.ascii_letters) for word in list]

Answered By: Blackgaurd

Answer 3

Strip first two chars and last char:

vals = ["ab1c", "ef2g", "hi3j"]

out = [val[2:-1] for val in vals]

Gives:

['1', '2', '3']

If you also want as ints (in question you ask for [1, 2, 3] as result) then:

out = [int(val[2:-1]) for val in vals]

Answered By: Anentropic

Answer 4

If the number of characters to be removed is fixed as in the original post, you can do the following:

list = ["ab1c", "ef2g", "hi3j"]
for i in range(len(list)):
    list[i]=int(list[i][2])
# list = [1, 2, 3]

Answered By: Lakshya Mahajan

How to remove characters from the end or start of every element in a Python list

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