Python - Ways to remove multiple empty spaces from string List

We are given a list of strings li =["Hello world", " Python is great ", " Extra spaces here "] we need to remove all extra spaces from the strings so that the output becomes ["Hello world", "Python is great' , "Extra spaces here"] .This can be done using methods like split() and join(), regular expressions or list comprehensions.

Using str.split() and str.join()

str.split() divides a string into substrings based on a delimiter while str.join() combines a list of substrings into a single string with a specified separator.

li = ["Hello   world", "   Python is  great  ", "   Extra  spaces here  "]

# Remove multiple spaces in each string using split and join
c = [' '.join(string.split()) for string in li]

print(c)

['Hello world', 'Python is great', 'Extra spaces here']

Explanation:

• We split each string in the list into words using split(), which automatically removes any extra spaces and then joins them back into a single string with a single space between words using join().
• This process ensures that all strings in the list are cleaned of unnecessary spaces, leaving only one space between words.

Using re.sub() with Regular Expressions

Using re.sub() with regular expressions allows you to efficiently replace multiple spaces in a string with a single space. It’s a powerful method for cleaning up text data by handling patterns of unwanted whitespace.

import re

s = ["Hello   world", "   Python is  great  ", "   Extra  spaces here  "]

# Remove multiple spaces using regex
li = [re.sub(r'\s+', ' ', string.strip()) for string in s]

print(li)

['Hello world', 'Python is great', 'Extra spaces here']

Explanation:

• re.sub(r'\s+', ' ', string.strip()) replaces consecutive spaces (matched by \s+) with a single space, and strip() removes any leading or trailing spaces from each string.
• List comprehension applies this operation to each string in the input list, s, resulting in a cleaned list of strings with only single spaces between words.

Using str.replace() in a Loop

Using str.replace() in a loop allows for replacing specific substrings in each string of a list or text. This method iterates through the strings applying the replacement operation for each occurrence of the target substring.

s = ["Hello   world", "   Python is  great  ", "   Extra  spaces here  "]

# Remove multiple spaces using replace in a loop
b = [string.replace('  ', ' ') for string in s]
# Repeat the replace step until no double spaces exist
a = [string.replace('  ', ' ') for string in b]

print(a)

['Hello world', ' Python is great ', ' Extra spaces here ']

Explanation:

• This method uses a list comprehension to iterate over each string in the list and replaces double spaces (' ') with single spaces (' ').
• Process is repeated to ensure all occurrences of multiple spaces are removed, leaving only single spaces between words.