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This tutorial showed you how to replace multiple characters in a string in Python.

Suppose we want to remove special characters from a string and replace them with spaces.

• The list of special characters to remove is !#$%^&*().
• Additionally, we want to replace commas with whitespace ,.
• The sample text we will manipulate.

A!!!,Quick,brown#$,fox,ju%m%^ped,ov&er&),th(e*,lazy,d#!og$$$

str.replace()Replace multiple characters in Python using

We can use strthe replace()method of to replace a substring with a different output.

replace()It accepts two parameters, the first one is the regex pattern you want to match the string against, and the second one is the replacement string for the matched string.

It replace()also has an optional third parameter in that accepts an integer that sets the maximum countnumber of replacements to be performed. If you pass 2as countthe parameter, replace()the function will only match and replace 2 instances in the string.

str.replace('Hello', 'Hi')will Hireplace all instances of in a string with Hello. If you have a string Hello Worldand run the replace function on it, it will become Hi World.

Let's use it on the sample text declared above replace. First we remove the special characters by looping over each character and replacing it with an empty string, and then we convert the commas to spaces.

txt = "A!!!,Quick,brown#$,fox,ju%m%^ped,ov&er&),th(e*,lazy,d#!og$$$"


def processString(txt):
    specialChars = "!#$%^&*()"
    for specialChar in specialChars:
        txt = txt.replace(specialChar, "")
    print(txt)  # A,Quick,brown,fox,jumped,over,the,lazy,dog
    txt = txt.replace(",", " ")
    print(txt)  # A Quick brown fox jumped over the lazy dog

This means that spCharsany characters within the square brackets will be replaced by an empty string, using txt.replace(spChars, '').

The string result of the first replace()function will be:

A, Quick, brown, fox, jumped, over, the, lazy, dog

The next call will replace replace()all instances of commas with single spaces.,

A Quick brown fox jumped over the lazy dog

Use re.sub()or re.subn()to replace multiple characters in Python

In Python, you can import rethe module, which has a large number of regex expression matching operations for you to use.

reTwo such functions in are sub()and subn().

Let's declare another string example for these methods. Suppose we want to replace all the numbers in a string with X.

txt = "Hi, my phone number is 089992654231. I am 34 years old. I live in 221B Baker Street. I have 1,000,000 in my bank account."

re.sub()Replacing multiple characters in Python using

This function has 3 main parameters. The first parameter accepts a regex pattern, the second parameter is a string to replace the matched pattern with, and the third parameter is the string to operate on.

Create a function that converts all the numbers in a string to X.

import re

txt = "Hi, my phone number is 089992654231. I am 34 years old. I live in 221B Baker Street. I have 1,000,000 in my bank account."


def processString3(txt):
    txt = re.sub("[0-9]", "X", txt)
    print(txt)


processString3(txt)

Output:

Hi, my phone number is XXXXXXXXXXXX. I am XX years old. I live in XXXB Baker Street. I have X,XXX,XXX in my bank account.

re.subn()Replacing multiple characters in Python

This function is essentially re.sub()the same as , but returns a tuple of the transformed string and the number of replacements.

import re

txt = "Hi, my phone number is 089992654231. I am 34 years old. I live in 221B Baker Street. I have 1,000,000 in my bank account."


def processString4(txt):
    txt, n = re.subn("[0-9]", "X", txt)
    print(txt)


processString4(txt)

Output:

Hi, my phone number is XXXXXXXXXXXX. I am XX years old. I live in XXXB Baker Street. I have X,XXX,XXX in my bank account.'

txt, n = re.subn("[0-9]", "X", txt)

In the above code snippet, the processed string is assigned to txtand the replacement counter is assigned to n.

re.subn()Useful if you want to make note of how many pattern groups there are as an indicator or for further processing .

Replacing multiple characters using translate()and in Pythonmaketrans()

translate()and maketrans()use a different approach than regex in that they utilize a dictionary to map old values ​​to new values.

maketrans()Accepts 3 arguments or a mapping of dictionaries.

• str1- The string to replace.
• str2- Replacement string for the above characters.
• str3- The string to be deleted.

maketrans()A mapping between original strings and their replacements.

translate()Accepts whatever maketrans()is returned, and then generates the translated string.

Let's say we want to convert all lowercase vowels in a string to uppercase and remove all x, y, and z in the string.

txt = "Hi, my name is Mary. I like zebras and xylophones."


def processString5(txt):
    transTable = txt.maketrans("aeiou", "AEIOU", "xyz")
    txt = txt.translate(transTable)
    print(txt)


processString5(txt)

Output:

HI, m nAmE Is MAr. I lIkE EbrAs And lOphOnEs.

translate()Convert all lowercase vowels to uppercase and remove all instances of x, y, and z.

Another way to use these methods is to use a single mapping dictionary instead of three parameters.

def processString6(txt):
    dictionary = {
        "a": "A",
        "e": "E",
        "i": "I",
        "o": "O",
        "u": "U",
        "x": None,
        "y": None,
        "z": None,
    }
    transTable = txt.maketrans(dictionary)
    txt = txt.translate(transTable)
    print(txt)

This will still produce processString5the same output as , but is implemented using a dictionary. You can use whichever method is more convenient for you.

In summary, there are various ways to replace multiple characters in a string by using built-in functions in Python or functions from imported libraries.

The most common approach is to use replace(). re.sub()and subn()is also fairly easy to use and learn. translate()uses a different approach as it does not rely on regular expressions to perform string manipulation, but rather on dictionaries and Maps.

If you wanted, you could even manually loop over the string using a for loop and add your own conditions to replace, just using substring()or split(), but this would be very inefficient and redundant. Python provides existing functions to do this for you, which is much easier than doing the tedious work yourself.