How do I use map and filter in Ruby?

How do I use map and filter in Ruby?

In Ruby, map is used to transform elements in an array, while filter (or select) is used to filter elements based on a condition.

Can you give me an example of using both?

Sure! Here's an example:

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

squared_even_numbers = numbers.select { |n| n.even? }.map { |n| n ** 2 }
puts squared_even_numbers

This will output [4, 16].

What if I want to use reject instead of select?

You can use reject to filter out elements that don't meet a condition. For example:

odd_numbers = numbers.reject { |n| n.even? }
puts odd_numbers

This will output [1, 3, 5].

Thanks! Are there any performance considerations I should be aware of?

Yes, using map and filter (or select) can create intermediate arrays, which may impact performance for large datasets. Consider using each_with_object for more complex transformations.