map() function in Python

Overview:

The built-in function map() does a mapping between the following
- a function - either a regular function defined using def or an anonymous function defined using lambda
- the parameters of the lambda function
- one or more python iterables

and returns an iterator.

The iterator when executed, for example using a, for loop – executes the function using its parameters. The parameters to the function are mapped to the python iterables passed to the map() function.
Number of times the iterator is executed is equal to the count of elements present in the shortest iterable passed to the map() function.

map() built-in function in Python

# Example Python program to apply lambda function to Python iterables

# using the built-in function map

multipliedBy2 = map(lambda x:x*x, [1,2,3,4,5]);

print("The sequence of numbers multiplied by 2:");

for i in multipliedBy2:

print(i);

The sequence of numbers multiplied by 2:

It should be made sure that the parameter count of the lambda function and the iterables count of the map function to be the same. Else an error similar to TypeError: <lambda>() takes 1 positional argument but 3 were given will be raised.

# Example Python program to apply a lambda function

# to multiple Python iterables using the map() built-in function

oddNumbers = [1, 3, 5, 7, 9];

evenNumbers = [2, 4, 6, 8, 10];

primeNumbers = [2, 3, 5, 7];

# invoke the map() built-in function

outputIterator = map(lambda x,y,z:x*y*z, oddNumbers, evenNumbers, primeNumbers);

# Print the return values of the lambda function by using the iterator

for i in outputIterator:

print(i);

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