Module: CameronPredictor

Included in:
Calcpace
Defined in:
lib/calcpace/cameron_predictor.rb

Overview

Module for predicting race times using the Cameron formula

An alternative to the Riegel formula (RacePredictor module) that uses an exponential correction to better account for physiological differences across distances. The correction is larger when predicting from shorter races, where anaerobic contribution is greater, and diminishes as the known distance approaches the target distance.

Formula: T2 = T1 × (D2/D1) × [(a + b × e^(-D1/c)) / (a + b × e^(-D2/c))]

Constants (calibrated for distances in km):

a = 0.000495
b = 0.000985
c = 1.4485

Reference: Dave Cameron, "A Critical Examination of Racing Predictions" (1997)

Constant Summary collapse

CAMERON_A =

Cameron formula constants (calibrated for distances in km)

0.000495
CAMERON_B = 
0.000985
CAMERON_C = 
1.4485

Instance Method Summary collapse

Instance Method Details

#predict_pace_cameron(from_race, from_time, to_race) ⇒ Float

Predicts pace per kilometer using the Cameron formula

Examples:

predict_pace_cameron('5k', '00:20:00', 'marathon')
#=> ~255.1 (approximately 4:15/km)

Parameters:

  • from_race (Numeric, String, Symbol) —

    known distance in kilometers or race name

  • from_time (String, Numeric) —

    time achieved at known distance

  • to_race (Numeric, String, Symbol) —

    target distance in kilometers or race name

Returns:

  • (Float) —

    predicted pace in seconds per kilometer



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# File 'lib/calcpace/cameron_predictor.rb', line 80

def predict_pace_cameron(from_race, from_time, to_race)
  predict_time_cameron(from_race, from_time, to_race) / race_distance(to_race)
end

#predict_pace_cameron_clock(from_race, from_time, to_race) ⇒ String

Predicts pace per kilometer using the Cameron formula, returned as a clock time string

Examples:

predict_pace_cameron_clock('5k', '00:20:00', 'marathon')
#=> '00:04:15'

Parameters:

  • from_race (Numeric, String, Symbol) —

    known distance in kilometers or race name

  • from_time (String, Numeric) —

    time achieved at known distance

  • to_race (Numeric, String, Symbol) —

    target distance in kilometers or race name

Returns:

  • (String) —

    predicted pace in HH:MM:SS format



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# File 'lib/calcpace/cameron_predictor.rb', line 94

def predict_pace_cameron_clock(from_race, from_time, to_race)
  convert_to_clocktime(predict_pace_cameron(from_race, from_time, to_race))
end

#predict_time_cameron(from_race, from_time, to_race) ⇒ Float

Predicts race time using the Cameron formula

Examples:

Predict marathon time from 10K

predict_time_cameron('10k', '00:42:00', 'marathon')
#=> ~10,654 seconds (approximately 2:57:34)

Predict 10K time from 5K

predict_time_cameron('5k', '00:20:00', '10k')
#=> ~2,546 seconds (approximately 42:26)

Parameters:

  • from_race (Numeric, String, Symbol) —

    known distance in kilometers (7.79, '7.79') or a standard race name ('5k', '10k', 'half_marathon', 'marathon', '100k', etc.)

  • from_time (String, Numeric) —

    time achieved at known distance (HH:MM:SS or seconds)

  • to_race (Numeric, String, Symbol) —

    target distance in kilometers or race name

Returns:

  • (Float) —

    predicted time in seconds

Raises:



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# File 'lib/calcpace/cameron_predictor.rb', line 42

def predict_time_cameron(from_race, from_time, to_race)
  from_distance = race_distance(from_race)
  to_distance   = race_distance(to_race)

  ensure_different_distances!(from_distance, to_distance)

  time_seconds = from_time.is_a?(String) ? convert_to_seconds(from_time) : from_time
  check_positive(time_seconds, 'Time')

  # Cameron formula: T2 = T1 × (D2/D1) × [cameron_factor(D1) / cameron_factor(D2)]
  time_seconds * (to_distance / from_distance) *
    (cameron_factor(from_distance) / cameron_factor(to_distance))
end

#predict_time_cameron_adjusted(from_race, from_time, to_race) ⇒ Hash

Predicts race time adjusted for environmental conditions using Cameron formula

Parameters:

  • from_race (Numeric, String, Symbol) —

    known distance in kilometers or race name

  • from_time (String, Numeric) —

    time achieved at known distance

  • to_race (Numeric, String, Symbol) —

    target distance in kilometers or race name

  • options (Hash) —

    environmental options (temperature, altitude, etc.)

Returns:

  • (Hash) —

    hash with adjusted prediction and penalty details



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# File 'lib/calcpace/cameron_predictor.rb', line 105

def predict_time_cameron_adjusted(from_race, from_time, to_race, **)
  predicted_seconds = predict_time_cameron(from_race, from_time, to_race)
  adjust_time(predicted_seconds, **)
end

#predict_time_cameron_clock(from_race, from_time, to_race) ⇒ String

Predicts race time using the Cameron formula, returned as a clock time string

Examples:

predict_time_cameron_clock('10k', '00:42:00', 'marathon')
#=> '02:57:34'

Parameters:

  • from_race (Numeric, String, Symbol) —

    known distance in kilometers or race name

  • from_time (String, Numeric) —

    time achieved at known distance

  • to_race (Numeric, String, Symbol) —

    target distance in kilometers or race name

Returns:

  • (String) —

    predicted time in HH:MM:SS format



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# File 'lib/calcpace/cameron_predictor.rb', line 66

def predict_time_cameron_clock(from_race, from_time, to_race)
  convert_to_clocktime(predict_time_cameron(from_race, from_time, to_race))
end