59 lines
1.2 KiB
Ruby
59 lines
1.2 KiB
Ruby
require "set"
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class PostVoteSimilarity
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class Element
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attr_reader :user_id, :score
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def initialize(user_id, score)
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@user_id = user_id
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@score = score
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end
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def <=>(rhs)
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score <=> rhs.score
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end
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end
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attr_reader :user_id
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def initialize(user_id)
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@user_id = user_id
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end
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# returns user ids with strong negative correlation
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def calculate_negative(limit = 10)
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posts0 = PostVote.negative_post_ids(user_id)
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set = SortedSet.new
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PostVote.positive_user_ids.each do |uid|
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posts1 = PostVote.positive_post_ids(uid)
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set.add(Element.new(uid, calculate_with_cosine(posts0, posts1)))
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end
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set.first(limit)
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end
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# returns user ids with strong positive correlation
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def calculate_positive(limit = 10)
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posts0 = PostVote.positive_post_ids(user_id)
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set = SortedSet.new
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PostVote.positive_user_ids.each do |uid|
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posts1 = PostVote.positive_post_ids(uid)
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set.add(Element.new(uid, calculate_with_cosine(posts0, posts1)))
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end
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set.first(limit)
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end
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def calculate_with_cosine(posts0, posts1)
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a = (posts0 & posts1).size
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div = Math.sqrt(posts0.size * posts1.size)
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if div == 0
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0
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else
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a / div
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end
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end
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end
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