Python Filter Exercises

Let’s check out some exercises that will help understand filter() function better.

Exercise 14-a

Using filter() function filter the list so that only negative numbers are left.

Hint 1

filter(f, list) can be useful. Make sure your function is a logical statement to facilitate the filtering process.

Hint 2

Since filter() function will return an iterator, you can use list() function to convert it to a proper Python list.

Solution

lst2 = list(filter(lambda x: x<0, lst1))
print(lst2)

Exercise 14-b

Using filter function, filter the even numbers so that only odd numbers are passed to the new list.

Hint 1

You can use filter(f, list). Make sure your function is a logical statement to facilitate the filtering process.

Hint 2

Since filter() function will return an iterator, you can use list() function to convert it to a proper Python list.

Solution

lst2 = list(filter(lambda x: x%2 == 1, lst1))

Exercise 14-c

Using filter() and list() functions and .lower() method filter all the vowels in a given string.

Hint 1

You can use filter(f, list). Make sure your function is a logical statement to facilitate the filtering process.

Hint 2

Since filter() function will return an iterator, you can use list() function to convert it to a proper Python list.

Hint 3

To create a lambda function with logical expression you can implement something like this:

lambda x: True if x in ….else False

Solution

lst = list(filter(lambda x: True if x.lower() in "aeiou" else False, str1))

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