Module: Prophet

Defined in:
lib/prophet.rb,
lib/prophet/plot.rb,
lib/prophet/version.rb,
lib/prophet/holidays.rb,
lib/prophet/forecaster.rb,
lib/prophet/stan_backend.rb

Defined Under Namespace

Modules: Holidays, Plot Classes: Error, Forecaster, StanBackend

Constant Summary collapse

VERSION = 
"0.3.2"

Class Method Summary collapse

Class Method Details

.anomalies(series, interval_width: 0.99, country_holidays: nil, cap: nil, verbose: false, **options) ⇒ Object

TODO better name for interval_width TODO DRY with forecast method



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# File 'lib/prophet.rb', line 94

def self.anomalies(series, interval_width: 0.99, country_holidays: nil, cap: nil, verbose: false, **options)
  df = Rover::DataFrame.new({"ds" => series.keys, "y" => series.values})
  df["cap"] = cap if cap

  m = Prophet.new(interval_width: interval_width, **options)
  m.logger.level = ::Logger::FATAL unless verbose
  m.add_country_holidays(country_holidays) if country_holidays
  m.fit(df)

  forecast = m.predict(df)
  # filter df["ds"] to ensure dates/times in same format as input
  df["ds"][(df["y"] < forecast["yhat_lower"]) | (df["y"] > forecast["yhat_upper"])].to_a
end

.forecast(series, count: 10, country_holidays: nil, cap: nil, verbose: false, **options) ⇒ Object

Raises:

  • (ArgumentError) 


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# File 'lib/prophet.rb', line 24

def self.forecast(series, count: 10, country_holidays: nil, cap: nil, verbose: false, **options)
  raise ArgumentError, "Series must have at least 10 data points" if series.size < 10

  # error early on unknown keywords
  m = Prophet.new(**options)

  # check type to determine output format
  # check for before converting to time
  keys = series.keys
  dates = keys.all? { |k| k.is_a?(Date) }
  time_zone = keys.first.time_zone if keys.first.respond_to?(:time_zone)
  utc = keys.first.utc? if keys.first.respond_to?(:utc?)
  times = keys.map(&:to_time)

  day = times.all? { |t| t.hour == 0 && t.min == 0 && t.sec == 0 && t.nsec == 0 }
  week = day && times.map { |k| k.wday }.uniq.size == 1
  month = day && times.all? { |k| k.day == 1 }
  quarter = month && times.all? { |k| k.month % 3 == 1 }
  year = quarter && times.all? { |k| k.month == 1 }

  freq =
    if year
      "YS"
    elsif quarter
      "QS"
    elsif month
      "MS"
    elsif week
      "W"
    elsif day
      "D"
    else
      diff = Rover::Vector.new(times).sort.diff.to_numo[1..-1]
      min_diff = diff.min.to_i

      # could be another common divisor
      # but keep it simple for now
      raise "Unknown frequency" unless (diff % min_diff).eq(0).all?

      "#{min_diff}S"
    end

  # use series, not times, so dates are handled correctly
  df = Rover::DataFrame.new({"ds" => series.keys, "y" => series.values})
  df["cap"] = cap if cap

  m.logger.level = ::Logger::FATAL unless verbose
  m.add_country_holidays(country_holidays) if country_holidays
  m.fit(df)

  future = m.make_future_dataframe(periods: count, include_history: false, freq: freq)
  future["cap"] = cap if cap
  forecast = m.predict(future)
  result = forecast[["ds", "yhat"]].to_a

  # use the same format as input
  if dates
    result.each { |v| v["ds"] = v["ds"].to_date }
  elsif time_zone
    result.each { |v| v["ds"] = v["ds"].in_time_zone(time_zone) }
  elsif utc
    result.each { |v| v["ds"] = v["ds"].utc }
  else
    result.each { |v| v["ds"] = v["ds"].localtime }
  end
  result.map { |v| [v["ds"], v["yhat"]] }.to_h
end

.new(**kwargs) ⇒ Object 



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# File 'lib/prophet.rb', line 20

def self.new(**kwargs)
  Forecaster.new(**kwargs)
end