Implement Utils.sort_tuples! for user-defined sorting
Akinori MUSHA
2 changed files with 80 additions and 0 deletions
+ 40
- 0
lib/utils.rb
@@ -79,4 +79,44 @@ module Utils |
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def self.pretty_jsonify(thing) |
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JSON.pretty_generate(thing).gsub('</', '<\/')
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end |
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+ |
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+ class TupleSorter |
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+ class SortableTuple |
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+ attr_reader :array |
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+ |
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+ # The <=> method will call orders[n] to determine if the nth element |
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+ # should be compared in descending order. |
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+ def initialize(array, orders = []) |
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+ @array = array |
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+ @orders = orders |
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+ end |
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+ |
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+ def <=> other |
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+ other = other.array |
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+ @array.each_with_index do |e, i| |
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+ case cmp = e <=> other[i] |
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+ when nil |
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+ return nil |
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+ when 0 |
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+ next |
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+ else |
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+ return @orders[i] ? -cmp : cmp |
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+ end |
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+ end |
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+ 0 |
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+ end |
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+ end |
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+ |
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+ class << self |
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+ def sort!(array, orders = []) |
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+ array.sort_by! do |e| |
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+ SortableTuple.new(e, orders) |
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+ end |
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+ end |
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+ end |
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+ end |
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+ |
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+ def self.sort_tuples!(array, orders = []) |
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+ TupleSorter.sort!(array, orders) |
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+ end |
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end |
+ 40
- 0
spec/lib/utils_spec.rb
@@ -114,4 +114,44 @@ describe Utils do |
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expect(cleaned_json).to include("<\\/script>")
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end |
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end |
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+ |
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+ describe "#sort_tuples!" do |
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+ let(:tuples) {
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+ time = Time.now |
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+ [ |
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+ [2, "a", time - 1], # 0 |
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+ [2, "b", time - 1], # 1 |
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+ [1, "b", time - 1], # 2 |
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+ [1, "b", time], # 3 |
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+ [1, "a", time], # 4 |
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+ [2, "a", time + 1], # 5 |
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+ [2, "a", time], # 6 |
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+ ] |
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+ } |
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+ |
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+ it "sorts tuples like arrays by default" do |
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+ expected = tuples.values_at(4, 2, 3, 0, 6, 5, 1) |
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+ |
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+ Utils.sort_tuples!(tuples) |
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+ expect(tuples).to eq expected |
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+ end |
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+ |
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+ it "sorts tuples in order specified: case 1" do |
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+ # order by x1 asc, x2 desc, c3 asc |
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+ orders = [false, true, false] |
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+ expected = tuples.values_at(2, 3, 4, 1, 0, 6, 5) |
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+ |
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+ Utils.sort_tuples!(tuples, orders) |
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+ expect(tuples).to eq expected |
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+ end |
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+ |
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+ it "sorts tuples in order specified: case 2" do |
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+ # order by x1 desc, x2 asc, c3 desc |
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+ orders = [true, false, true] |
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+ expected = tuples.values_at(5, 6, 0, 1, 4, 3, 2) |
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+ |
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+ Utils.sort_tuples!(tuples, orders) |
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+ expect(tuples).to eq expected |
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+ end |
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+ end |
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end |