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Python map() Function

The map() function executes a given function to each element of an iterable (such as lists, tuples, etc.).

Syntax​

map(function, iterables)

map() Parameters​

Python map() function parameters:

ParameterConditionDescription
functionRequiredA function to which map passes each element of the given iterable.
iterableRequiredAn iterable which is to be mapped. You can pass one or more iterables.
note

You can pass more than one iterable to the map() function.

map(function, iterable1, iterable2, ...)

map() Return Value​

Python map() function returns a map object, which can be easily converted to lists, tuples, etc.

Examples​

Example 1: Compute Square Numbers with map() function​

Let's use the map() function to calculate the square of a list of numbers:

# Define a function to square a number
def square(number):
    return number * number

# Apply square() to each item of a list
numbers = [1,  2,  3,  4]
squared_numbers = map(square, numbers)

# Convert to list for printing
result = list(squared_numbers)
print(result)  # Output: [1,  4,  9,  16]

output

[1,  4,  9,  16]

Example 2: Compute Cube Numbers with map() function​

Let's use the map() function to calculate the cube of a list of numbers:

# Define a function that returns the cube of a number
def cube(num):
    return num**3

# Create a list of numbers
my_list = [1,  2,  3,  4,  5]

# Use map() to apply the cube function to each item in the list
new_list = list(map(cube, my_list))
print(new_list)  # Output: [1,  8,  27,  64,  125]

output

[1,  4,  9,  16]
note

num1 has 3 items, and num3 has 5 items. When you use map() with num1 and num3 as arguments, the lambda function is applied only to the first three items of num3 because num1 is the shortest iterable. The remaining two items in num3 are not used because map() stops when the shortest iterable is exhausted.

Example 3: Converting Strings to Integers with map() function​

Let's convert a list of string numbers to a list of numbers using the map() function

# Given a list of string numbers
str_nums = ["4", "8", "6", "5", "3", "2", "8", "9", "2", "5"]

# Use map() to convert each string to an integer
int_nums = map(int, str_nums)

# Convert the map object to a list
result = list(int_nums)
print(result)  # Output: [4,  8,  6,  5,  3,  2,  8,  9,  2,  5]

output

[4,  8,  6,  5,  3,  2,  8,  9,  2,  5]

Example 4: String Modification using map() function​

map() function can be used to modify strings.

For example, convert each string in the list into a list of individual characters:

languages=['Python', 'Java','Rust']
# convert each string into list of individual characters 
result= list(map(list, languages))
print(result)

output

[['P', 'y', 't', 'h', 'o', 'n'], ['J', 'a', 'v', 'a'], ['R', 'u', 's', 't']]

Example 5: map() function and Lambdas​

In a map() function, we can also use a lambda function instead of a regular function. For example:

numbers = (1, 2, 3, 4)
result = map(lambda x: x*x, numbers)

# convert to list and print it
print(list(result)) # Output: [1, 4, 9, 16]

output

[1, 4, 9, 16]

Example 6: Add Multiple Lists using map() and lambda​

num1 = [1, 2, 3]
num2 = [10, 20, 30]
num3 = [100, 200, 300, 400, 500]

# add corresponding items from the num1 and num2 lists
result1 = map(lambda n1, n2: n1+n2, num1, num2)
print(list(result1)) # Output: [11, 22, 33]
result2 = map(lambda n1, n2: n1+n2, num1, num3)
print(list(result2)) # Output:

output

[11, 22, 33]
[101, 202, 303]

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