What is the difference between map and filter functions when processing data collections?

The map and filter functions are used for processing collections but serve different purposes:

• map(function, iterable) — applies the function to all elements and returns an iterator with the results.

• filter(function, iterable) — filters elements, passing only those for which the function returns True.

Example:

numbers = [1, 2, 3, 4, 5]

# map: square each element
squares = list(map(lambda x: x**2, numbers))  # [1, 4, 9, 16, 25]

# filter: select only even numbers
evens = list(filter(lambda x: x % 2 == 0, numbers))  # [2, 4]

In summary:

• map transforms each element.
• filter selects elements based on a condition.