Table of Contents
Map function is a generator function that applies another function to elements
of the iterable that is passed as an argument. The basic structure of a map()
function is as follows:
map(function, iterable)
map(function, iterable, *iterables)The first parameter function is function itself that transforms the element to
the iterable. The function can either be a regular function or a lambda.
Reference: https://docs.python.org/3/library/functions.html#map
def capitalize_and_ascii_sum(word: str):
"""
This method capitalizes the word and finds out the sum of ASCII value of
all characters of a word
"""
return sum(ord(x) for x in word.capitalize())
animals = ['cat', 'dog', 'cow']
transformed_data = map(capitalize_and_ascii_sum, animals)
print(list(transformed_data)) # [280, 282, 297]Here the first parameter capitalize_and_ascii_sum is a callable that is mapped
to each data of the list animals.
We can also use lambda instead of a function for transforming the data.
numbers = [1, 2, 3, 4, 5]
squares = map(lambda x: x ** 2, numbers)
print(list(squares)) # [1, 4, 9, 16, 25]Here, the lambda squares the number that is passed and maps the square values
of all the elements of the list numbers.
We can also map 2 or more iterables to find out the resulting iterable. This method is useful when we have to perform operations between different data such as sum of each element of list.
If we pass 2 iterables of different length, it will map the value until the shortest iterable gets exhausted.
food = ['apple', 'potato', 'chicken', 'banana']
product = ['juice', 'chips', 'chilly', 'shake']
dishes = map(lambda a, b: f'{a} {b}', food, product)
print(list(dishes)) # ['apple juice', 'potato chips', 'chicken chilly', 'banana shake']