I have two arrays of integers, e.g.
a = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
b = [7, 8, 9]
I would like to repeatedly duplicate the value of 'b' to get a perfectly matching array lengths like this:
a = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
b = [7, 8, 9, 7, 8, 9, 7, 8, 9, 7]
We can assume that a.length > b.length
Assuming you mean
a = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
b = [7, 8, 9]
then you can do:
b.cycle.take(a.length) #=> [7, 8, 9, 7, 8, 9, 7, 8, 9, 7]
<script src="//repl.it/embed/JJ3x/2.js"></script>See Array#cycle and Enumerable#take for more details.
take.I would have used Array#cycle had it been available, but since it was taken I thought I'd suggest some alternatives (the first being my fav).
a = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
b = [7, 8, 9]
[*b*(a.size/b.size), *b[0, a.size % b.size]]
#=> [7, 8, 9, 7, 8, 9, 7, 8, 9, 7]
Array.new(a.size) { |i| b[i % b.size] }
#=> [7, 8, 9, 7, 8, 9, 7, 8, 9, 7]
b.values_at(*(0..a.size-1).map { |i| i % b.size })
#=> [7, 8, 9, 7, 8, 9, 7, 8, 9, 7]
a.map.with_index { |_,i| b[i%b.size] }
bgoes into length ofa,ntimes you can writeb*n.