What is map function in Python?

The map function in Python is a built-in function that takes in two or more inputs: a function and one or more iterables, such as lists or tuples. The function is applied to each element of the iterable(s) and returns a new iterator that contains the results.

Here's an example of how to use the map function to apply a function to each element of a list:

def double(x):

    return x * 2

numbers = [1, 2, 3, 4]

doubled_numbers = map(double, numbers)

print(list(doubled_numbers))  # [2, 4, 6, 8]

In this example, we defined a function double that takes in a single argument x and returns x * 2. We then created a list of numbers and passed it as the second argument to map, along with the double function as the first argument. The map function applied the double function to each element in the numbers list and returned a new iterator that contains the doubled values. We used the list function to convert the iterator to a list and printed the result.

It's important to note that the map function returns an iterator, not a list. This means that the elements are generated on the fly and are not stored in memory all at once. This can be useful when working with large datasets, as it allows you to process the data one element at a time, rather than loading everything into memory at once.

You can also use the map function with multiple iterables. In this case, the function should take in as many arguments as there are iterables. For example:

def multiply(x, y):

    return x * y

numbers1 = [1, 2, 3, 4]

numbers2 = [5, 6, 7, 8]

product = map(multiply, numbers1, numbers2)

print(list(product))  # [5, 12, 21, 32]

In this example, we defined a function multiply that takes in two arguments x and y and returns their product. We then passed two lists, numbers1 and numbers2, to the map function, along with the multiply function as the first argument. The map function applied the multiply function to each pair of elements (one from each list) and returned a new iterator that contains the products.

Overall, the map function is a useful tool for applying a function to each element of an iterable and returning a new iterator with the results. It can be especially helpful when working with large datasets, as it allows you to process the data one element at a time, rather than loading everything into memory at once.