Python - Filter list elements starting with given Prefix

We are given a list we need to filter list elements that are starting with given prefix. For example, a = ['apple', 'banana', 'avocado', 'apricot', 'cherry'] and given prefix is p = 'ap' we need to filter all the list elements that are starting with given prefix so that output should be ['apple', 'apricot'].

Using List Comprehension

List comprehension iterates through each element in the list and checks if it starts with given prefix using startswith(). If the condition is met element is included in new filtered list.

a = ['apple', 'banana', 'avocado', 'apricot', 'cherry']
p = 'ap'

# Filter elements starting with the given prefix using list comprehension
b = [word for word in a if word.startswith(p)]  
print(b)

['apple', 'apricot']

Explanation:

• List comprehension iterates through each word in the list a and checks if it starts with the prefix p using the startswith() method.
• Words that meet the condition are added to the new list f which contains the filtered elements.

Using filter() with lambda

filter() function filters elements from the list based on the condition defined in the lambda function which checks if each element starts with given prefix result is an iterator which is converted into a list for further use.

a = ['apple', 'banana', 'avocado', 'apricot', 'cherry']
p = 'ap'

# Filter elements starting with the given prefix using filter() and lambda
b = list(filter(lambda word: word.startswith(p), a))  
print(b)

['apple', 'apricot']

Explanation:

• filter() function applies the lambda function to each word in the list a, checking if the word starts with the prefix p using startswith().
• Result of filter() is an iterator which is converted to a list storing the words that match the condition in f.

Using for Loop

A for loop iterates through each element in the list checking if it starts with the given prefix using startswith(). If condition is met element is appended to a new list containing filtered words.

a = ['apple', 'banana', 'avocado', 'apricot', 'cherry']
p = 'ap'

# Filter elements starting with the given prefix using a for loop
b = []
for word in a:
    if word.startswith(p):
        b.append(word)  
print(b)

['apple', 'apricot']

Explanation:

• for loop iterates through each word in the list a checking if it starts with prefix p using startswith().
• If condition is satisfied word is appended to list f which stores filtered elements.