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Editorial Team
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Asked: 2026-06-13T10:14:46+00:00

The source (already ordered properly): rows = [{key=>[2012, 10]}, {key=>[2012, 9]}, {key=>[2011, 7]}] Desired

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The source (already ordered properly):

rows = [{"key"=>[2012, 10]}, {"key"=>[2012, 9]}, {"key"=>[2011, 7]}]

Desired result:

[[2012, [10, 9]], [2011, [7]]]
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1 Answer

  1. Editorial Team
    rows.map {|row| row.values.flatten}.inject({}) {|h,r| h[r[0]].nil? ? h[r[0]] = [r[1]] : h[r[0]] << r[1];h }.to_a
# [[2012, [10, 9]], [2011, [7]]]

    or 

    rows.map {|row| row.values.flatten}.inject({}) {|h,r| h[r[0]] ||= []; h[r[0]] << r[1];h }.to_a
# [[2012, [10, 9]], [2011, [7]]]
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