The map Method in Ruby
Nurudeen Ibrahim
Apr 18, 2022
![The map Method in Ruby](/img/Ruby/ag-feature-image---use-map-method-in-ruby.webp)
The map
method is one of Ruby’s most popular enumerable methods. It’s used to transform an array into another one.
Example Codes:
numbers = [2, 4, 6]
doubles = numbers.map do |n|
n * 2
end
puts doubles
Output:
[4, 8, 12]
The above code maps through the numbers
array, multiply each element by two, and produce a new doubles
array. This is how the map
method works.
Note that there is also a collect
method, an alias to map
, and both work similarly. We can show that by rewriting the above code using the collect
method.
Example Codes:
numbers = [2, 4, 6]
doubles = numbers.collect do |n|
n * 2
end
puts doubles
Output:
[4, 8, 12]
Although the map
method produces a new array, there’s also a map!
which works the same way as map
but also mutates the original array.
Example Codes:
numbers = [2, 4, 6]
doubles = numbers.map! do |n|
n * 2
end
puts doubles
puts numbers
Output:
[4, 8, 12]
[4, 8, 12]
Looking at the output above, you would notice that the original numbers
array has been mutated and now has the same value as doubles
.