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# Python – Remove String from String List

This particular article is indeed a very useful one for Machine Learning enthusiast as it solves a good problem for them. In Machine Learning we generally encounter this issue of getting a particular string in huge amount of data and handling that sometimes becomes a tedious task. Lets discuss certain way outs to solve this problem.

Method #1: Using remove() This particular method is quite naive and not recommended to use, but is indeed a method to perform this task. remove() generally removes the first occurrence of K string and we keep iterating this process until no K string is found in list.

## Python3

 `# Python 3 code to demonstrate``# Remove K String from String List``# using remove()` `# initializing list``test_list ``=` `[``"bad"``, ``"GeeksforGeeks"``, ``"bad"``, ``"is"``, ``"best"``, ``"bad"``]` `# Printing original list``print``(``"Original list is : "` `+` `str``(test_list))` `# initializing K``K ``=` `"bad"` `# using remove() to``# Remove K String from String List``while``(K ``in` `test_list):``    ``test_list.remove(K)` `# Printing modified list``print``(``"Modified list is : "` `+` `str``(test_list))`

Output :

```Original list is : ['bad', 'GeeksforGeeks', 'bad', 'is', 'best', 'bad']
Modified list is : ['GeeksforGeeks', 'is', 'best']```

Time Complexity: O(n), where n is the number of elements in the list “test_list”.
Auxiliary Space: O(1), constant extra space is required

Method #2: Using List Comprehension More concise and better approach to remove all the K strings, it just checks if the string is not K and re-makes the list with all strings that are not K.

## Python3

 `# Python 3 code to demonstrate``# Remove K String from String List``# using list comprehension` `# initializing list``test_list ``=` `[``"bad"``, ``"GeeksforGeeks"``, ``"bad"``, ``"is"``, ``"best"``, ``"bad"``]` `# Printing original list``print``(``"Original list is : "` `+` `str``(test_list))` `# initializing K``K ``=` `"bad"` `# using list comprehension to``# Remove K String from String List``test_list ``=` `[i ``for` `i ``in` `test_list ``if` `i !``=` `K]` `# Printing modified list``print``(``"Modified list is : "` `+` `str``(test_list))`

Output :

```Original list is : ['bad', 'GeeksforGeeks', 'bad', 'is', 'best', 'bad']
Modified list is : ['GeeksforGeeks', 'is', 'best']```

Time Complexity: O(n)
Auxiliary Space: O(n), where n is length of list.

Method #3 : Using join(),replace(),split() and remove() methods

## Python3

 `# Python 3 code to demonstrate``# Remove K String from String List` `# initializing list``test_list ``=` `[``"bad"``, ``"GeeksforGeeks"``, ``"bad"``, ``"is"``, ``"best"``, ``"bad"``]` `# Printing original list``print` `(``"Original list is : "` `+` `str``(test_list))` `# initializing K``K ``=` `"bad"` `x``=``"-"``.join(test_list)``x``=``x.replace(K,"")``a``=``x.split(``"-"``)``while``("" ``in` `a ):``    ``a.remove("")``# Printing modified list``print` `(``"Modified list is : "` `+` `str``(a))`

Output

```Original list is : ['bad', 'GeeksforGeeks', 'bad', 'is', 'best', 'bad']
Modified list is : ['GeeksforGeeks', 'is', 'best']```

Here’s another approach to removing a string ‘K’ from a string list, using a filter:

## Python

 `# Python 3 code to demonstrate``# Remove K String from String List``# using filter()`` ` `# initializing list``test_list ``=` `[``"bad"``, ``"GeeksforGeeks"``, ``"bad"``, ``"is"``, ``"best"``, ``"bad"``]`` ` `# Printing original list``print``(``"Original list is : "` `+` `str``(test_list))`` ` `# initializing K``K ``=` `"bad"`` ` `# using filter to Remove K String from String List``test_list ``=` `list``(``filter``(``lambda` `x: x!``=``K, test_list))`` ` `# Printing modified list``print``(``"Modified list is : "` `+` `str``(test_list))`

Output

```Original list is : ['bad', 'GeeksforGeeks', 'bad', 'is', 'best', 'bad']
Modified list is : ['GeeksforGeeks', 'is', 'best']```

This approach uses the filter() function to create a filtered list of elements from test_list that are not equal to K. The list() function is then used to convert the filtered list into a list.

Time complexity: O(n), where n is the number of elements in the list test_list.

Space complexity: O(n), since a new list is created.

My Personal Notes arrow_drop_up