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require 'benchmark'
module Enumerable
# duplicates
def duplicates_1
h1 = {}
h2 = {}
each {|i|
h2[i] = true if h1[i]
h1[i] = true
}
h2.keys
end
def duplicates_2
inject(Hash.new(0)){|h,v| h[v]+=1; h}.reject{|k,v| v==1}.keys
end
# uniq_by
def uniq_by_1 #:yield:
h = {}; inject([]) {|a,x| h[yield(x)] ||= a << x}
end
def uniq_by_2
inject({}) { |h,x| h[yield(x)] ||= x; h }.values
end
end
#
Benchmark.bmbm do |x|
n = 10000
a = [1,1,2,3,4,4,5,6,7,7]
# duplicates
x.report("duplicates_1") do
n.times { a.duplicates_1 }
end
x.report("duplicates_2") do
n.times { a.duplicates_2 }
end
# uniq_by
x.report("uniq_by_1") do
n.times { a.uniq_by_1{ |x| x } }
end
x.report("uniq_by_2") do
n.times { a.uniq_by_2{ |x| x } }
end
end
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