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rubyhashaggregategrouping

Collapse a log by date into an array of hashes

A local variable named log contains an array of hashes with timestamped events like so:

log = [
  {time: 201201, x: 2},
  {time: 201201, y: 7},
  {time: 201201, z: 2},
  {time: 201202, a: 3},
  {time: 201202, b: 4},
  {time: 201202, c: 0}
]

I need to collapse the log by date into an array of hashes containing one entry per day:

result = [
  {time: 201201, x: 2, y: 7, z: 2},
  {time: 201202, a: 3, b: 4, c: 0},
]
Solution 
  • log.group_by {|e| e[:time] }.map {|_,v| v.reduce(:merge) }