Python - Removing unwanted characters from string

Python is a very commonly used program used for different purposes like Web Development, Data Science, Machine learning and also to perform different processes with automation. While working on any field of application we have to work on one common thing called string. So in this article we are going to learn how to remove unwanted characters from string.

Replacement

In this method we simply specify the unwanted element and then that element is removed and an empty place is present in the string. We can understand it in a more better way through the following example

Example

def unwanted_string_words(data, sentence):  #Input is provided
    for sent in sentence:   #Check different characters in string
        data = data.replace(sent, '')   #Remove unwanted characters from string
    return data 

# Example
whole_string = "Hi! My Name Is, John"
to_be_removed = "!,"
final_string =unwanted_string_words(whole_string, to_be_removed)
print(final_string)  

Output

The output of the above code will be as follows:

Hi My Name Is John 

re module

In this method we will use the regular expression module to remove the characters from the string. We can understand its use from the following example:

Example

import re   # Do not forget to import the re module or else error might occur

def unwanted_string_words(data, sentence):   # The input is provided
    pattern = "[" + re.escape("".join(sentence)) + "]"  #We will join all the characters using re.escape
    return re.sub(pattern, "", data)   # We will then use re.sub to remove the unwanted characters

# Example
whole_string = "Hi! My Name Is, John"
to_be_removed = "!,"
final_string =unwanted_string_words(whole_string, to_be_removed)
print(final_string)  

Output

The output of the above example will be as follows:

Hi My Name Is John 

List Comprehension

By this method we will create a new list only of the wanted characters after removing all the unwanted characters from the original string. We can understand it clearly through the following example:

Example

def unwanted_string_words(data, sentence):   #The input is provided
   return ''.join([sent for sent in data if sent not in sentence])   # All the characters in the string are checked and the characters which are not to be removed sre moved to a new list and some characters are removed.

# Example
whole_string = "Hi! My Name Is, John"
to_be_removed = "!,"
final_string =unwanted_string_words(whole_string, to_be_removed)
print(final_string)  

Output

The output of the above provided example will be as follows:

Hi My Name Is John 

Translate Method

This is a very useful method to remove characters from a list of dictionaries. The characters to be removed are specified in the translation table and they are removed accordingly. The example of removing characters with the help of translate method is as follows:

Example

def unwanted_string_words(data, sentence):  #The input of string is provided
    translation_table_characters = str.maketrans('', '', ''.join(sentence))    # With the help pf str.maketrans a translation table is made and the characters to be removed are specified     
    return data.translate(translation_table_characters)  #The str.translate is used to remove the characters and provide an empty space

# Example
whole_string = "Hi! My Name Is, John"
to_be_removed = "!,"
final_string =unwanted_string_words(whole_string, to_be_removed)
print(final_string) 

Output

The output of the above mentioned example will be as follows:

Hi My Name Is John 

Filter Function

As the name suggests, in this method we will specify some filter to remove some characters from our string. This is one of the simplest methods of removing characters from a string. We can understand it in a more clear way through the following example:

Example

def unwanted_string_words(data, sentence):  # The input of string is given
    unwanted_string_words = filter(lambda sent: sent not in sentence, data)  #Filter will check all the characters of the string
    # Lambda will be used to look for the unwanted characters in the whole string
    return ''.join(unwanted_string_words)  #After removing the unwanted characters, the remaining characters are moved to a new list 

# Example
whole_string = "Hi! My Name Is, John"
to_be_removed = "!,"
final_string =unwanted_string_words(whole_string, to_be_removed)
print(final_string) 

Output

The output of the above example will be as follows:

Hi My Name Is John 

List & Joining

In this method, whole of the string is created into characters and then all the characters are checked and all the unwanted characters are removed from the list. We can understand it in a more better way through the following example:

Example

def unwanted_string_words(data, sentence):  # The input of string is provided 
    unwanted_string_words = [sent for sent in data if sent not in sentence]  # List comprehension will be used to check each characters and the unwanted ones will be removed
    return ''.join(unwanted_string_words)  #The remaining characters will be joined to form a string

# Example
whole_string = "Hi! My Name Is, John"
to_be_removed = "!,"
final_string =unwanted_string_words(whole_string, to_be_removed)
print(final_string) 

Output

The output of the above example provided will be as follows:

Hi My Name Is John 

Conclusion

The editing of the strings present in the program is common process followed by a programmer. So, it is very necessary to know about all the above mentioned methods to be an efficient and fast programmer. One can refer this article to learn about many different methods to remove characters from string.