Question

I need to values for a graph, and I want all values with the same date to merge.

This is the array I have now:

[ ['2012-10-09', 1], ['2012-10-09', 2], ['2012-10-10', 1], ['2012-10-10', 4], ['2012-10-10', 1], ['2012-10-11', 3] ]

And the result I want:

[ ['2012-10-09', 3], ['2012-10-10', 6], ['2012-10-11', 3] ]

Is there a simple way to do this?

Answer 1

Simple as that:

a.inject({}) { |h,(date, count)| h[date] ||= 0; h[date] += count; h }.to_a