Python - Swap commas and dots in a String

Last Updated : 27 Dec, 2024

In this article, we'll explore how to swap commas and dots in a string in Python.

Using str.translate()

str.translate() that allows for character substitution within a string using a translation table. It enables quick transformations, such as swapping characters like commas and dots.

Example:

Python 
# Create a translation table 
# to map commas to dots and vice versa
t = str.maketrans(',.', '.,')
s = "14, 625, 498.002"

# Swap commas and dots
res = s.translate(t)
print(res)

Output
14. 625. 498,002

Let's understand different methods to swap commas and dots in a string.

Table of Content

Using str.replace()

str.replace() allows us to swap characters by first replacing them with a temporary placeholder. This approach enables efficient swapping of commas and dots in a string without direct mapping.

Example:

Python 
s = "14, 625, 498.002"

# Replace commas with a temporary character
s = s.replace(',', '#')

# Replace dots with commas
s = s.replace('.', ',')

# Replace the temporary character with dots
s = s.replace('#', '.')
print(s)

Output
14. 625. 498,002

Using regular expression

re.sub() uses regular expressions for flexible text replacements. By applying a callback function, it efficiently swaps commas and dots based on their context.

Example:

Python 
import re
s = "14, 625, 498.002"

# Swap commas and dots with lambda function
s = re.sub(r'[.,]', lambda x: ',' if x.group(0) == '.' else '.', s)
print(s)

Output
14. 625. 498,002

Using List comprehension

List comprehension iterate over the string and swap commas and dots. The modified characters are then joined back into a string using join().

Example:

Python 
s = "14, 625, 498.002"

# Swap commas and dots 
s = ''.join(['.' if char == ',' else ',' if char == '.' else char for char in s])
print(s)

Output
14. 625. 498,002

Using for Loop

Loop iterate through the string and manually swap commas and dots. Characters are added to a list and then joined to form the final string.

Example:

Python 
s = "14, 625, 498.002"

# Initialize empty list to store result
res = []

for char in s:
  
    # If character is comma, append dot
    if char == ',':
        res.append('.')
        
    # If character is dot, append comma
    elif char == '.':
        res.append(',')
        
    # Otherwise, append the character as is
    else:
        res.append(char)

# Join list of characters back into string
s = ''.join(res)
print(s)

Output
14. 625. 498,002
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