Duplicate elements of array in ruby

Question

I find a lot of reference about removing duplicates in ruby but I cannot find how to create duplicate.

If I have an array like [1,2,3] how can I map it to a

Answer 1

@Ursus answer is the most clean, there are possible solutions:

a = [1, 2, 3]
a.zip(a).flatten
#=> [1, 1, 2, 2, 3, 3]

Or

a.inject([]) {|a, e| a << e << e} #  a.inject([]) {|a, e| n.times {a << e}; a}
=> [1, 1, 2, 2, 3, 3]

Or

[a, a].transpose.flatten # ([a] * n).transpose.flatten
=> [1, 1, 2, 2, 3, 3]