What Are Python Lambda Functions?

I learned python lambda functions from a codecademy.com tutorial – highly recommend.

My definition:

A one-liner for defining a function.

Example:

add_two = lambda x: x + 2

add_two(5) //prints 7

add_two(100) //prints 102

add_two(-2) //prints 0

Notes:

• Similar to defining a function with keyword   def
• The variable after keyword lambda is your input
• Anything after the colon (:) is what you would be returning
• Whatever variable you’re assigning the lambda function is the name of the function

Adding if… else statements to our lambda functions:

Template:

<WHAT TO RETURN IF STATEMENT IS TRUE> if <IF STATEMENT> else <WHAT TO RETURN IF STATEMENT IS FALSE>

Example:

check_if_a_grade = lambda grade: "Got an A!" if grade >= 90 else "Did not get an A…"

Notes:

• Lambda functions only work as a one line command
• Helpful if you’re going to use the function only once

More Examples:

contains_a = lambda word: True if 'a' in word else False

print(contains_a("banana")) //True

print(contains_a("apple")) //True

print(contains_a("cherry")) //False

long_string = lambda str: True if len(str) > 12 else False

print(long_string("short")) //False

print(long_string("photosynthesis")) //True

ends_in_a = lambda str: True if str[-1] == 'a' else False

print(ends_in_a("data")) //True

print(ends_in_a("aardvark")) //False

even_or_odd = lambda num: 'even' if num % 2 == 0 else 'odd'

print(even_or_odd(10)) //even

print(even_or_odd(5)) //odd

ones_place = lambda num: num % 10

print(ones_place(123)) //3, because 3 is in the one's place of 123

print(ones_place(4)) //4