Ruby: Map Function to Array

By Xah Lee. Date:

Map Function to Array

Use array.map {…} method on array object to create a new array. Example:

# ruby

def ff(n)
 n*n
end

aa = 0..4 # array 0 to 4

p aa.map {|xx| ff xx} # [0, 1, 4, 9, 16]

Use method array.map! {…} to have the original array modified.

Removing Elements in a Array

To remove elements, use “select” method and pass it a block.

In Ruby, many methods can take a “block” argument. The “block” is a kind of lambda expression. The syntax has the form: object_name.method_name { |x| expression_on_x}. Example:

# ruby

aa = 0..10 # a array 0 to 10

p aa.select { |xx| xx % 2 == 0 } # [0, 2, 4, 6, 8, 10]

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