Python change letter in string

Python Replace Character in String

When it comes to data cleaning and text processing, replacing the string characters in python is a critical task. There might be some spelling issues, formatting issues with the garbage character that should be removed necessarily before processing the data further. In this article, we will refer to some common methods to replace characters over different types of strings in python but before that, let us get some basic idea of python strings in detail.

What is String in Python?

Strings in python is a sequence of Unicode characters wrapped around single or double-quotes. You can also use triple quotes when the string is multi-line. However, python does not have a character data type unlike any other programming language and therefore, a string with length 1 is considered to be a single character. Hence, strings are ordered collections of characters that are immutable in nature. This means that you cannot add, update or delete the string after it is created. If any operations are to be performed, a copy of an original string is created and updated accordingly. The below example shows the python string in detail.

For Example

a = "Compile With Favtutor" print(a)

How to Replace a Character in a String in Python?

Below are 6 common methods used to replace the character in strings while programming in python.

1) Using slicing method

Slicing is a method in python which allows you to access different parts of sequence data types like strings, lists, and tuples. Using slicing, you can return a range of characters by specifying the start index and end index separated by a colon and return the part of the string. Similarly, here you can choose the character to be replaced by the slicing method and simply replace it with the new character as shown in the below example:

For Example

str = 'favtutor' index = 0 new_character = 'F' str = str[:index] + new_character + str[index+1:] print(str)

2) Using replace() method

Python possesses many in-built functions to make programming easy and replace() method is one of them. replace() method helps to replace the occurrence of the given old character with the new character or substring. The method contains the parameters like old(a character that you wish to replace), new(a new character you would like to replace with), and count(a number of times you want to replace the character). Take a look at the below example for a better understanding of the method.

For Example

str = "Compile with favtutor" result = str.replace("f", "F") print(result)

3) Using the list data structure

In this approach, first, you have to convert the given string into a list data type and then replace the character at the given index with the new character. Later you have to join the list of characters together to form a result string again. Check out the below example explaining the working of this approach.

For Example

str = 'favtutor' index = 0 new_character = 'F' temp = list(str) temp[index] = new_character str = "".join(temp) print(str)

4) Replace multiple characters with the same character

You can replace multiple characters in the given string with the new character using the string indexes. For this approach, you can make use of for loop to iterate through a string and find the given indexes. Later, the slicing method is used to replace the old character with the new character and get the final output.

For Example

str = 'Python' indexes = [2, 4, 5] new_character = 'a' result = '' for i in indexes: str = str[:i] + new_character + str[i+1:] print(str)

5) Replace multiple characters with different characters

This approach is a slight modification of the above method where you can replace multiple characters with different characters at the same time. Just like the above example, you can make use of for loop to iterate through string characters and replace them using the slicing method. Take a look at the below example for a better understanding.

For Example

str = 'Python' indexes = 2: 'a', 4: 'b', 5: 'c'> result = '' # Replace multiple characters with different replacement characters for index, replacement in indexes.items(): str = str[:index] + indexes[index] + str[index + 1:] print(str)

6) Using regex module

Python regex module specifically handles text data to find substrings, replace strings, or any other task. You can import this module in the python program and replace the old character with a new one effectively. The method takes three parameters i.e. the pattern that needs to be replaced, the replacement string, and the original string in which the substring has to be replaced. Check out the below example to learn the working of the regex module:

For Example

import re address = '211B Baker Street' new_address = re.sub('Street', 'St.', address) print(new_address)

Conclusion

We covered many examples displaying different ways to replace the characters of the string in python. As the string is one of the most important data structures in python, sometimes it is necessary to modify them according to the need of the program. Hence, it is highly recommended to learn and understand all of the above methods to replace the characters of strings and make your programming skills faster and efficient.

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About The Author

Shivali Bhadaniya

I’m Shivali Bhadaniya, a computer engineer student and technical content writer, very enthusiastic to learn and explore new technologies and looking towards great opportunities. It is amazing for me to share my knowledge through my content to help curious minds.

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Python: Replace a character in a string

In this article, we will discuss different ways to replace a character in string in python.

Overview:

Replace all occurrences of a character in string in python using replace()

In python, the String class (Str) provides a method replace() to replace the sub-strings in a string. We can use that to replace all the occurrences of a character in a string with another character. For example,

org_string = "This is a sample string" # Replace all occurrences of a character in string in python new_string = org_string.replace('s', 'X') print(new_string)

Here we passed the character to be replaced ‘s’ as the first argument and character ‘X’ as the second argument. Then replace() method returned a copy of the original string by replacing all the occurrences of character ‘s’ with the ‘X’.

Frequently Asked:

As strings are immutable in Python, i.e., we cannot change its contents. Therefore replace() function returns a copy of the string with the replaced content.

Replace the first two occurrences of a character in string in python

Instead of replacing all occurrences of a character in a string, we can replace only the first few occurrences of a character in a string by passing the count argument in the replace() function i.e.

org_string = "This is a sample string" # Replace first two occurrences of a character in string new_string = org_string.replace('s', 'X', 2) print(new_string)

Here we passed the character to be replaced ‘s’ as the first argument and character ‘X’ as the second argument. Then we passed the third argument as 2. The third argument is optional and it tells the replace() function that how many occurrences of given sub-string need to be replaced.

Then replace() method returned a copy of the original string by replacing only first two occurrences of ‘s’ with the ‘X’.
As strings are immutable in Python, i.e., we cannot change its contents. Therefore replace() function returns a copy of the string with the replaced content.

Replace a character in a string using regex in python

Python provides a regex module (re), and in this module, it provides a function sub() to replace the contents of a string based on patterns. We can use this re.sub() function to substitute/replace all occurrences of a character in the string,

import re # Replace a character in string using regex in python new_string = re.sub('s', 'X', org_string) print(new_string)

Here we passed the character to be replaced ‘s’ as the first argument and character ‘X’ as the second argument in the sub() function. Then we passed the third argument as the original string.

Sub() function used the first argument as a pattern and replaced all the matches of that pattern with the given replacement string, i.e., ‘X’. So, it replaced all the occurrences of character ‘s’ with the character ‘X’. As strings are immutable in python i.e., we cannot change its contents. Therefore sub() function of the regex module returns a copy of the string with the replaced content.

Replace a character in a string using for loop in python

Initialize an empty string and then iterate over all characters of the original string. During iteration, add each character to the new string. But for the characters that needs replacement, use the replacement character instead. For example,

to_replace = 's' replaced = 'X' # Replace a character in string using for loop new_string = '' for elem in org_string: if elem == to_replace: new_string += replaced else: new_string += elem print(new_string)

It replaced all the occurrences of character ‘s’ with the ‘X’.

As strings are immutable in Python, i.e., we cannot change its contents. Therefore, we created a new copy of the string with the replaced content.

We can replace a character in a string with another character in python by using the replace() function or sub() function or a for loop.

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