Reputation: 329
I am trying to conceptualize the iteration of two loops
numbers_array = [1,2,3,4,5,6,7,8,9,10]
add_to_array = [1,2,3,4]
While the numbers_array
iterates, add_to_array
iterates simultaneously adding both elements together at the same time. The caveat is once add_to_array
reaches the end, it starts over adding its element to the next index in numbers_array
. So at numbers_array[4]
we would be adding add_to_array[0]
then adding numbers_array[5]
to add_to_array[1]
and so on. This process would repeat until we reach the end of the numbers_array
.
Any input would be greatly appreciated!
Upvotes: 0
Views: 80
Reputation: 11193
Another option:
numbers_array.map { |e| e + add_to_array.rotate!.last }
# => [2, 4, 6, 8, 6, 8, 10, 12, 10, 12]
Drawback: add_to_array is mutated by rotate!
Upvotes: 0
Reputation: 110675
add_to_array.zip(*numbers_array.each_slice(add_to_array.size)).
map { |a| a.sum { |e| e.to_i } }
#=> [16, 20, 13, 16]
e.to_i
is needed to convert nil
values to zeros. See NilClass#to_i.
Upvotes: 0
Reputation: 121000
You are looking for Enumerable#zip
and Enumerable#cycle
:
numbers_array = [1,2,3,4,5,6,7,8,9,10]
#⇒ [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
add_to_array = [1,2,3,4]
#⇒ [1, 2, 3, 4]
numbers_array.zip(add_to_array.cycle)
#⇒ [[1, 1], [2, 2], [3, 3], [4, 4], [5, 1],
# [6, 2], [7, 3], [8, 4], [9, 1], [10, 2]]
Now do whatever you want with the array returned. E.g. to reduce the zipped result summing elements, map ro Enumerable#sum
:
numbers_array.zip(add_to_array.cycle).map(&:sum)
#⇒ [2, 4, 6, 8, 6, 8, 10, 12, 10, 12]
Upvotes: 8
Reputation: 13417
It works by using the %
operator to cycle through the indexes.
numbers_array = [1,2,3,4,5,6,7,8,9,10]
add_to_array = [1,2,3,4]
numbers_array.map.with_index do |n, i|
n + add_to_array[i % add_to_array.length]
end
A cool method that's similar, if you didn't want to start over at the next array, would be .zip
https://apidock.com/ruby/Array/zip
Upvotes: 0