/* 

  Grass in Picat.

  This is a port of the R2 model Grass.cs
  
  We observe that the grass is wet. Did it rain?
  
  Output from the R2 model:
  """
  Mean: 0.699
  Variance: 0.21061
  Number of accepted samples = 790
  """

  Cf my Gamble model gamble_grass.rkt

  This program was created by Hakan Kjellerstrand, hakank@gmail.com
  See also my Picat page: http://www.hakank.org/picat/

*/

import ppl_distributions, ppl_utils.
import util.

main => go.

/*
  var : rain
  Probabilities:
  true: 0.7112424195303996
  false: 0.2887575804696004
  mean = [true = 0.711242,false = 0.288758]

  var : cloudy
  Probabilities:
  true: 0.5838905302441300
  false: 0.4161094697558700
  mean = [true = 0.583891,false = 0.416109]

  var : sprinkler
  Probabilities:
  false: 0.5691183330741720
  true: 0.4308816669258280
  mean = [false = 0.569118,true = 0.430882]

  var : wet roof
  Probabilities:
  false: 0.5062976208987716
  true: 0.4937023791012284
  mean = [false = 0.506298,true = 0.493702]

  var : temp2
  Probabilities:
  true: 0.9583268542994868
  false: 0.0416731457005131
  mean = [true = 0.958327,false = 0.0416731]

  var : temp3
  Probabilities:
  true: 0.9273829886487327
  false: 0.0726170113512673
  mean = [true = 0.927383,false = 0.072617]

*/
go ?=>
  reset_store,
  run_model(10_000,$model,[show_probs_trunc,mean]),
  nl,
  % show_store_lengths,
  % fail,
  nl.
go => true.
  
  
model() =>
  Cloudy = flip(0.5),
  Rain   = condt(Cloudy,flip(0.8),flip(0.2)),
  Sprinkler = condt(Cloudy,flip(0.1),flip(0.5)),
  Temp1 = flip(0.7),
  WetRoof = check((Temp1,Rain)),

  Temp2 = flip(0.9),
  Temp3 = flip(0.9),

  WetGrass = check( ( (Temp2,Rain) ; (Temp3,Sprinkler)) ),

  % We observe that the grass is wet.
  % Did it rain?
  observe(WetGrass),
  
  if observed_ok then
    add("rain",Rain),
    add("cloudy",Cloudy),
    add("sprinkler",Sprinkler),
    add("wet roof",WetRoof),
    add("temp2",Temp2),
    add("temp3",Temp3),
  end.