Sha256: e203495111a45d712c08cbdb05cde188d2a82db950ae341ce076709af237b327
Contents?: true
Size: 779 Bytes
Versions: 10
Compression:
Stored size: 779 Bytes
Contents
module Enumerable
# Like #group_by, but maps the second value returned from the block.
#
# a = [1,2,3,4,5]
# a.map_by{ |e| [e % 2, e + 1] }
# #=> { 0=>[3,5], 1=>[2,4,6] }
#
# Works well with a hash too.
#
# h = {"A"=>1, "B"=>1, "C"=>1, "D"=>2, "E"=>2}
# h.map_by{ |k,v| [v, k.downcase] }
# #=> {1=>["a", "b", "c"], 2=>["d", "e"]}
#
# If a second value is not returned, #map_by acts like #group_by.
#
# h = {"A"=>1, "B"=>1, "C"=>1, "D"=>2, "E"=>2}
# h.map_by{ |k,v| v }
# #=> {1=>[["A",1], ["B",1], ["C",1]], 2=>[["D",2], ["E",2]]}
#
def map_by #:yield:
res = {}
each do |a|
k,v = yield(*a)
if v
(res[k] ||= []) << v
else
(res[k] ||= []) << a
end
end
res
end
end
Version data entries
10 entries across 9 versions & 2 rubygems