What is the difference between map and filter in programming?

What is the difference between map and filter in programming?

The map function applies a given function to each item in a list and returns a new list with the results. In contrast, filter applies a function that returns a boolean value, keeping only the items that evaluate to true.

Can you give me an example of how to use both functions?

Sure! For map, if you have a list of numbers and want to double them, you can use map like this: map(lambda x: x * 2, numbers). For filter, if you want to keep only even numbers, you can use: filter(lambda x: x % 2 == 0, numbers).

Are there any performance differences between them?

Yes, map generally has better performance when you need to transform all items, while filter is more efficient when you only need a subset of items. However, the actual performance can depend on the specific use case and data size.

Can I chain map and filter together?

Absolutely! You can chain them like this: filter(lambda x: x % 2 == 0, map(lambda x: x * 2, numbers)). This will first double the numbers and then filter out the odd results.