Class: Growthbook::Util

Inherits:
Object
  • Object
show all
Defined in:
lib/growthbook/util.rb

Overview

internal use only

Class Method Summary collapse

Class Method Details

.check_rule(actual, op, desired) ⇒ Object 



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# File 'lib/growthbook/util.rb', line 10

def self.check_rule(actual, op, desired)
  # Check if both strings are numeric so we can do natural ordering
  # for greater than / less than operators
  numeric = begin
    (!Float(actual).nil? && !Float(desired).nil?)
  rescue StandardError
    false
  end

  case op
  when '='
    numeric ? Float(actual).to_d == Float(desired).to_d : actual == desired
  when '!='
    numeric ? Float(actual).to_d != Float(desired).to_d : actual != desired
  when '>'
    numeric ? Float(actual) > Float(desired) : actual > desired
  when '<'
    numeric ? Float(actual) < Float(desired) : actual < desired
  when '~'
    begin
      !!(actual =~ Regexp.new(desired))
    rescue StandardError
      false
    end
  when '!~'
    begin
      actual !~ Regexp.new(desired)
    rescue StandardError
      false
    end
  else
    true
  end
end

.choose_variation(num, ranges) ⇒ Object

Chose a variation based on a hash and range



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# File 'lib/growthbook/util.rb', line 99

def self.choose_variation(num, ranges)
  ranges.each_with_index do |range, i|
    return i if num >= range[0] && num < range[1]
  end
  -1
end

.format_js_digits(digits, point) ⇒ Object

Lays out digits d1..dk with x = 0.d1..dk * 10**point, as ECMAScript Number::toString does



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# File 'lib/growthbook/util.rb', line 170

def self.format_js_digits(digits, point)
  k = digits.length
  return digits + ('0' * (point - k)) if k <= point && point <= 21
  return "#{digits[0, point]}.#{digits[point..-1]}" if point.positive? && point <= 21
  return "0.#{'0' * -point}#{digits}" if point > -6 && point <= 0

  e = point - 1
  fraction = k > 1 ? ".#{digits[1..-1]}" : ''
  "#{digits[0]}#{fraction}e#{e.negative? ? '-' : '+'}#{e.abs}"
end

.get_bucket_ranges(num_variations, coverage, weights) ⇒ Object

Determine bucket ranges for experiment variations



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# File 'lib/growthbook/util.rb', line 73

def self.get_bucket_ranges(num_variations, coverage, weights)
  # Make sure coverage is within bounds
  coverage = 1.0 if coverage.nil?
  coverage = 0.0 if coverage.negative?
  coverage = 1.0 if coverage > 1

  # Default to equal weights
  weights = get_equal_weights(num_variations) if !weights || weights.length != num_variations

  # If weights don't add up to 1 (or close to it), default to equal weights
  total = weights.sum
  weights = get_equal_weights(num_variations) if total < 0.99 || total > 1.01

  # Convert weights to ranges
  cumulative = 0.0
  ranges = []
  weights.each do |w|
    start = cumulative
    cumulative += w
    ranges << [start, start + (coverage * w)]
  end

  ranges
end

.get_equal_weights(num_variations) ⇒ Object 



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# File 'lib/growthbook/util.rb', line 62

def self.get_equal_weights(num_variations)
  return [] if num_variations < 1

  weights = []
  (1..num_variations).each do |_i|
    weights << (1.0 / num_variations)
  end
  weights
end

.get_hash(seed:, value:, version:) ⇒ Float?

Returns Hash, or nil if the hash version is invalid.

Returns:

  • (Float, nil) —

    Hash, or nil if the hash version is invalid



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# File 'lib/growthbook/util.rb', line 46

def self.get_hash(seed:, value:, version:)
  return (FNV.new.fnv1a_32(value + seed) % 1000) / 1000.0 if version == 1
  return (FNV.new.fnv1a_32(FNV.new.fnv1a_32(seed + value).to_s) % 10_000) / 10_000.0 if version == 2

  nil
end

.get_query_string_override(id, url, num_variations) ⇒ Object

Get an override variation from a url querystring e.g. http://localhost?my-test=1 will return 1 for id my-test



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# File 'lib/growthbook/util.rb', line 108

def self.get_query_string_override(id, url, num_variations)
  # Skip if url is empty
  return nil if url == '' || id.nil?

  # Parse out the query string
  parsed = URI(url)
  parsed_query = parsed.query
  return nil if parsed_query.nil?

  qs = URI.decode_www_form(parsed_query)

  # Look for `id` in the querystring and get the value
  vals = qs.assoc(id)
  return nil unless vals

  val = vals.last
  return nil unless val

  # Parse the value as an integer
  n = begin
    Integer(val)
  rescue StandardError
    nil
  end

  # Make sure the integer is within range
  return nil if n.nil?
  return nil if n.negative?
  return nil if n >= num_variations

  n
end

.in_namespace?(hash_value, namespace) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/growthbook/util.rb', line 53

def self.in_namespace?(hash_value, namespace)
  return false if namespace.nil?

  n = get_hash(seed: "__#{namespace[0]}", value: hash_value, version: 1)
  return false if n.nil?

  n >= namespace[1] && n < namespace[2]
end

.in_range?(num, range) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/growthbook/util.rb', line 141

def self.in_range?(num, range)
  num >= range[0] && num < range[1]
end

.js_number_to_s(number) ⇒ String

Formats a number like JavaScript's String(number) (ECMAScript Number::toString), e.g. 2.0 -> "2", 0.000002 -> "0.000002", 1e21 -> "1e+21".

Parameters:

  • number (Numeric) —

    An Integer is formatted as the double JavaScript would parse

Returns:

  • (String) 


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# File 'lib/growthbook/util.rb', line 150

def self.js_number_to_s(number)
  x = number.to_f
  return 'NaN' if x.nan?
  return x.positive? ? 'Infinity' : '-Infinity' if x.infinite?
  return '0' if x.zero?
  return "-#{js_number_to_s(-x)}" if x.negative?

  # Float#to_s gives the same shortest round-trip digits as JavaScript, but
  # switches to scientific notation at different thresholds
  mantissa, exponent = x.to_s.split('e')
  whole, fraction = mantissa.to_s.split('.')
  all_digits = "#{whole}#{fraction}"
  digits = all_digits.sub(/\A0+/, '')
  # x = 0.digits * 10**point
  point = whole.to_s.length + exponent.to_i - (all_digits.length - digits.length)
  digits = digits.sub(/0+\z/, '')
  format_js_digits(digits, point)
end