Python list with empty string

Python: Check if any string is empty in a list?

In this article we will discuss different ways to check if a list contains any empty or blank string in python.

Use any() and List Comprehension to check if list contains any empty string

We have created a function to check if a string is empty. It will also consider a string empty if it contains only white spaces,

import re def is_empty_or_blank(msg): """ This function checks if given string is empty or contain only shite spaces""" return re.search("^\s*$", msg)

Now let’s use this function to check if a list contains any empty or blank string,

# Create a list of string list_of_str = ['11', 'This', 'is ', 'a', '', ' ', 'sample'] # Check if list contains any empty string or string with spaces only result = any([is_empty_or_blank(elem) for elem in list_of_str]) if result: print('Yes, list contains one or more empty strings') else: print('List does not contains any empty string')

Frequently Asked:

Yes, list contains one or more empty strings

It confirms that our list contains one or more empty / blank string.

Logic of this approach:

Using list comprehension, we created a bool list from our original list. If an element in bool list is True it means that corresponding element
in original list is an empty or blank string.

• First Create an empty bool list.
• Then iterate over each element in the list using list comprehension and for each element in the list,
  • Check if it is empty or not using is_empty_or_blank() function.
    • If element is an empty string,
      • Then add True in the bool list.
      • Add bool to the bool list.
      • If yes
        • Then it confirms that our original list also contains an empty or blank list.
        • There is no empty/blank string in original list.

        Check if list contains any empty string using for loop

        Instead of using list comprehension, we can also implement the logic of previous solution using for loop i.e,

        # Create a list of string list_of_str = ['11', 'This', 'is ', 'a', '', ' ', 'sample'] result = False # iterate over all the elements in list to check if list contains any empty string for elem in list_of_str: # Check if string is empty or contain only spaces if is_empty_or_blank(elem): result = True break; if result: print('Yes, list contains one or more empty string') else: print('List does not contains any empty string')

        Yes, list contains one or more empty strings

        It confirms that our list contains one or more empty or blank string.

        Here we iterated over all elements of list and for each element we checked if it is an empty string or not. As soon as it encountered the first empty or blank string, it stopped checking the remaining elements. Whereas, if there are no empty strings in list, then it confirms only after check all elements in list.

        The complete example is as follows,

        import re def is_empty_or_blank(msg): """ This function checks if given string is empty or contain only shite spaces""" return re.search("^\s*$", msg) def main(): print('*** Check if list contains any empty string using list comprehension ***') # Create a list of string list_of_str = ['11', 'This', 'is ', 'a', '', ' ', 'sample'] # Check if list contains any empty string or string with spaces only result = any([is_empty_or_blank(elem) for elem in list_of_str]) if result: print('Yes, list contains one or more empty strings') else: print('List does not contains any empty string') print('*** Check if list contains any empty string using for loop ***') result = False # iterate over all the elements in list to check if list contains any empty string for elem in list_of_str: # Check if string is empty or contain only spaces if is_empty_or_blank(elem): result = True break; if result: print('Yes, list contains one or more empty string') else: print('List does not contains any empty string') if __name__ == '__main__': main()

        *** Check if list contains any empty string using list comprehension *** Yes, list contains one or more empty strings *** Check if list contains any empty string using for loop *** Yes, list contains one or more empty string

        Related posts:

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        Python – Create List of N Empty Strings

        

        💬 Challenge: Given an integer n . How to create a list of n empty strings » in Python?

        • Given n=0 . Create list [] .
        • Given n=3 . Create list [», », »] .
        • Given n=5 . Create list [», », », », »] .

        Method 1: List Multiplication

        You can create a list of n empty strings using the list concatenation (multiplication) operator on a list with one empty string using the expression [»] * n . This replicates the same identical empty string object to which all list elements refer. But as strings are immutable, this cannot cause any problems through aliasing.

        def create_list_empty_strings(n): return [''] * n print(create_list_empty_strings(0)) # [] print(create_list_empty_strings(3)) # ['', '', ''] print(create_list_empty_strings(5)) # ['', '', '', '', '']

        Method 2: List Comprehension

        You can create a list of n empty strings by using list comprehension statement [» for _ in range(n)] that uses the range() function to repeat the creation and addition of an empty string n times.

        def create_list_empty_strings(n): return ['' for _ in range(n)] print(create_list_empty_strings(0)) # [] print(create_list_empty_strings(3)) # ['', '', ''] print(create_list_empty_strings(5)) # ['', '', '', '', '']

        Method 3: For Loop and append()

        To create a list of n empty strings without special Python features, you can also create an empty list and use a simple for loop to add one empty string at a time using the list.append() method.

        def create_list_empty_strings(n): my_list = [] for i in range(n): my_list.append('') return my_list print(create_list_empty_strings(0)) # [] print(create_list_empty_strings(3)) # ['', '', ''] print(create_list_empty_strings(5)) # ['', '', '', '', '']

        Summary

        There are three best ways to create a list with n empty strings.

        1. List concatenation [»] * n
        2. List comprehension [» for _ in range(n)]
        3. Simple for loop with list append(») on an initially empty list

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        4 Ways to Remove Empty Strings from a List

        

        Here are 4 ways to remove empty strings from a list in Python:

        (1) Using a list comprehension:

        new_list = [x for x in list_with_empty_strings if x != '']

        (2) Using for loop:

        new_list = [] for x in list_with_empty_strings: if x != '': new_list.append(x)

        (3) Using filter:

        new_list = list(filter(None, list_with_empty_strings))

        (4) Using filter and lambda:

        new_list = list(filter(lambda x: x != '', list_with_empty_strings))

        Next, you’ll see how to apply each of the above approaches using simple examples.

        Examples of removing empty strings from a list in Python

        Case 1: Using a list comprehension

        Suppose that you have the following list that contains empty strings:

        list_with_empty_strings = ['blue', 'green', '', 'red', '', 'yellow', 'orange', ''] print(list_with_empty_strings)

        As you can see, there are currently 3 empty strings in the list (as highlighted in yellow):

        ['blue', 'green', '', 'red', '', 'yellow', 'orange', ''] 

        The goal is to remove those 3 empty strings from the list in Python.

        You can then use a list comprehension to remove those empty strings:

        list_with_empty_strings = ['blue', 'green', '', 'red', '', 'yellow', 'orange', ''] new_list = [x for x in list_with_empty_strings if x != ''] print(new_list)

        The empty strings would now be removed:

        ['blue', 'green', 'red', 'yellow', 'orange'] 

        Case 2: Using for loop

        Alternatively, you can use a for loop to remove the empty strings:

        list_with_empty_strings = ['blue', 'green', '', 'red', '', 'yellow', 'orange', ''] new_list = [] for x in list_with_empty_strings: if x != '': new_list.append(x) print(new_list)

        You’ll get the same list without the empty strings:

        ['blue', 'green', 'red', 'yellow', 'orange'] 

        (3) Using filter:

        You can achieve the same results using a filter as follows:

        list_with_empty_strings = ['blue', 'green', '', 'red', '', 'yellow', 'orange', ''] new_list = list(filter(None, list_with_empty_strings)) print(new_list)

        As before, you’ll get the same list without the empty strings:

        ['blue', 'green', 'red', 'yellow', 'orange'] 

        (4) Using filter and lambda:

        Finally, you may apply a filter and lambda to remove the empty strings in the list:

        list_with_empty_strings = ['blue', 'green', '', 'red', '', 'yellow', 'orange', ''] new_list = list(filter(lambda x: x != '', list_with_empty_strings)) print(new_list)

        ['blue', 'green', 'red', 'yellow', 'orange'] 

        Источник