Converting a generic history of quizzes (times and results) to an Ebisu model (given initial half-life and model parameters) to a Memorize schedule

quizHistoryToEbisuToMemorize.py

import ebisu
from memorizesrs import schedule
from datetime import datetime, timedelta
from math import inf

learnTime = datetime(2020, 1, 27, 0, 0, 0)
reviewTimes = [
    learnTime + timedelta(hours=1.1), learnTime + timedelta(hours=4.4),
    learnTime + timedelta(hours=22.0), learnTime + timedelta(days=2.4)
]
reviewResults = [False, True, True, True]
initialModel = ebisu.defaultModel(0.25, 2.0)  # initial half-life = quarter-hour, α=β=2


def historyToEbisuModel(learnTime, initialModel, reviewTimes, reviewResults):
  """Convert history of quizzes to Ebisu model"""
  assert len(reviewTimes) == len(reviewResults)
  previousTime = learnTime
  model = initialModel
  for (reviewTime, result) in zip(reviewTimes, reviewResults):
    model = ebisu.updateRecall(model, result, (reviewTime - previousTime).total_seconds() / 3600)
    previousTime = reviewTime
  return model


def ebisuModelToMemorizeInterval(model, q=10.0, T=inf):
  """Use an Ebisu model to draw a MEMORIZE interval"""
  return schedule(lambda t: ebisu.predictRecall(initialModel, t, exact=True), q, T)


def ebisuModelToInterval(model, pRecall):
  """When with an Ebisu model decay to a certain recall probability?"""
  return ebisu.modelToPercentileDecay(model, pRecall)


ebisuModel = historyToEbisuModel(learnTime, initialModel, reviewTimes, reviewResults)
dueIn = ebisuModelToMemorizeInterval(ebisuModel, q=10.0, T=inf)
print("MEMORIZE Quiz due in {} hours".format(dueIn))
print("Ebisu    Quiz due in {} hours".format(ebisuModelToInterval(ebisuModel, 0.25)))

try:
  import pandas as pd
  print("\n\nMonte Carlo analysis:\n")
  for model in [initialModel, ebisuModel]:
    print("Ebisu halflife={} hours".format(ebisu.modelToPercentileDecay(model)))
    print(pd.DataFrame([ebisuModelToMemorizeInterval(model) for n in range(10_000)]).describe())
except:
  print("Didn't run pandas analysis")