Hướng dẫn dùng string remove python

In this article, we will discuss four different ways to delete multiple characters from a string in python.

Nội dung chính

• Delete multiple characters from string using translate[] function
• Delete multiple characters from string using regex
• Delete multiple characters from string using replace[]
• Delete multiple characters from string using filter[] and join[]

Nội dung chính

• Delete multiple characters from string using translate[] function
• Delete multiple characters from string using regex
• Delete multiple characters from string using replace[]
• Delete multiple characters from string using filter[] and join[]

Suppose we have a string “A small sample String for testing” and a list of characters that need to be deleted from string i.e.

list_of_chars = ['s', 't', 'a', 'A', ' ']

Let’s see how to delete these characters from the string.

Delete multiple characters from string using translate[] function

The string class in python, provides a function translate[]. It accepts a translation table as an argument and replaces the characters in string based on the mapping in the translation table. We can create a translation table, where each character that we want to be deleted from string, will be mapped to an empty string. Like,

• Ascii value of ‘s’ : ”
• Ascii value of ‘t’ : ”
• Ascii value of ‘a’ : ”
• Ascii value of ‘A’ : ”
• Ascii value of ‘ ‘ : ”

We will pass this translation table to translate[] function as an argumment. Due to which translate[] function will replace all the occurrences of these characters with an empty string. Basically it will remove all the occurrences of these characters from the string. For example,

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sample_str = 'A small sample String for testing'

# A list containing multiple characters, that needs to be deleted from the string.
list_of_chars = ['s', 't', 'a', 'A', ' ']

# Create a mapping table to map the characters 
# to be deleted with empty string
translation_table = str.maketrans['', '', ''.join[list_of_chars]]

# Remove multiple characters from the string
sample_str = sample_str.translate[translation_table]

print[sample_str]

Output:

mllmpleSringforeing

It removed all occurrences of multiple characters from the string.

Delete multiple characters from string using regex

In Python, the regex module provides a function to replace the contents of a string based on a matching regex pattern. Signature of function is like this,

sub[pattern, replacement_str, original_str]

We can use this to remove multiple characters from a string. For this we need to pass a regex pattern that matches all the occurrences of the given characters. Also, as a replacement string we need to pass a empty string. For example, let’s see how to delete characters ‘s’, ‘t’, ‘a’, ‘A’ and ‘ ‘ from a string using regex,

import re

sample_str = 'A small sample String for testing'

# A list containing multiple characters, that needs to be deleted from the string.
list_of_chars = ['s', 't', 'a', 'A', ' ']

# Create regex pattern to match all characters in list
pattern = '[' +  ''.join[list_of_chars] +  ']'

# Remove multiple characters from the string
sample_str = re.sub[pattern, '', sample_str]

print[sample_str]

Output:

mllmpleSringforeing

It removed all occurrences of ‘s’, ‘t’, ‘a’, ‘A’ and ‘ ‘ from the string.

Delete multiple characters from string using replace[]

The string class provides a function to replace a sub-string in a string i.e.

str.replace[to_be_replaced, replacement]

It accepts two arguments i.e. the string to be replaced and the replacement string. It returns a copy of the calling string object but with the changed contents i.e. after replacing all the occurrences of sub-string to_be_replaced with the given replacement string. So, to delete multiple characters from a string using replace[] function, follow this logic:

Iterate over all the characters to be deleted and for each character, pass it to the replace[] function along with the empty string. For example,

sample_str = 'A small sample String for testing'

# A list containing multiple characters, that needs to be deleted from the string.
list_of_chars = ['s', 't', 'a', 'A', ' ']

# Remove multiple characters from the string
for character in list_of_chars:
    sample_str = sample_str.replace[character, '']

print[sample_str]

Output:

mllmpleSringforeing

It removed all occurrences of multiple characters i.e. ‘s’, ‘t’, ‘a’, ‘A’ and ‘ ‘ from the string.

Delete multiple characters from string using filter[] and join[]

In Python, you can use the filter[] function to filter all the occurences of a characters from a string. Steps are as follows,

• Create a lambda function, that accepts a character as an argument and returns True only if the passed character matches with any of the given the characters that need to be deleted.
• Along with the string to be modified, pass the above created lambda function to the filter[] function, as the conditional argument.
• filter[] function loops through all characters of string and yields only those characters for which lambda function returns True i.e. all characters except the characters that need to be deleted.
• Use join[] function to combine all yielded characters returned by filter[] function.
• Assign back the joined string returned by join[] function to the original variable. It will give an effect that we have deleted multiple characters from the string.

For example,

sample_str = 'A small sample String for testing'

# A list containing multiple characters, that needs to be deleted from the string.
list_of_chars = ['s', 't', 'a', 'A', ' ']

# Filter multiple characters from string
filtered_chars = filter[lambda item: item not in list_of_chars, sample_str]

# Join remaining characters in the filtered list
sample_str = ''.join[filtered_chars]

print[sample_str]

Output:

mllmpleSringforeing

Summary:

We learned about different ways to delete multiple characters from a string in python.