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Versions: 5
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Contents
# -*- coding: utf-8 -*-
class RailsDataExplorer
module Statistics
# Responsibilities:
# * Provide random categorical data. Useful for testing and demo data.
#
class RngCategory
# @param categories [Array<Object>] the pool of available categories.
# @param category_probabilities [Array, optional] probability of each category.
# @param rng [Proc, optional] lambda to generate random numbers which will
# be mapped to categories.
def initialize(categories, category_probabilities = nil, rng = lambda { Kernel.rand })
@categories, @category_probabilities, @rng = categories, category_probabilities, rng
@category_probabilities ||= @categories.map { |e| @rng.call }
@category_probabilities = normalize_category_probabilities
@category_order = compute_category_order
end
# Returns a random category
def rand
r_v = @rng.call
rnd = @category_order.detect { |e|
e[:threshold] >= r_v
}
rnd[:category]
end
protected
def normalize_category_probabilities
total = @category_probabilities.inject(0) { |m,e| m += e }
@category_probabilities.map { |e| e / total.to_f }
end
def compute_category_order
category_order = []
running_sum = 0
@categories.each_with_index { |e, idx|
running_sum += @category_probabilities[idx]
category_order << { category: e, threshold: running_sum }
}
category_order
end
end
end
end
Version data entries
5 entries across 5 versions & 1 rubygems