python

map() function in python

To apply a function on all elements of an iterable element like a list we can use the python map() function.

my_list = [2, 3, 5, 9]

def multiply(item):
  return item * item

result = map(multiply, my_list)

result = list(result)

# -> [4, 9, 25, 81]

Python map() function is used to apply a given function to the elements of a list. We can also use the map to convert a sequence (list) into another set of values. The map() function takes two arguments, first the function that needs to be applied on a set of values, and second the sequence you want to run through. Let's take a look at some examples.

Steps by step description of map() function applied in the above code snippet

1. We have defined a list variable my_list that contains multiple integers.

2. Defined a function named multiply that takes the list item as a parameter and returns the value by multiplying the item itself.

3. Using map() function and passing multiply function and my_list to it. Storing the result in result named variable.

map(function, iterable) parameters

There are two parameters that are passed to the map() function in python.

function: It is the method that is applied to each element of an iterable list or item.

Iterable: You can use a list or other iterable items as this parameter.

Basic syntax of map() function

map(myfunc, iter_item)

Use of lambda expression in map() function

my_list = [2, 3, 5, 9]

result = map(lambda item: item * item, my_list)

result = list(result)

# -> [4, 9, 25, 81]

You can also use lambda expressions inside map() function to apply some expression on all the items of the list. In the above code, we have generated new list from a list of items that multiply itself.

Pass multiple lists to map() function

list1 = [4, 6, 9, 10]
list2 = [5, 2, 4, 5]

result = map(lambda x, y: x * y, list1, list2)

result = list(result)

# -> [20, 12, 36, 50]

print(result)

We can pass more than one list in the python map() function. Using the above code we are multiplying two list items with their respective index.

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