"""File 07discreteMixture.py

:author: Michel Bierlaire, EPFL
:date: Sun Sep  8 00:06:20 2019

 Example of a discrete mixture of logit (or latent class model) 
 Three alternatives: Train, Car and Swissmetro
 SP data
"""
import pandas as pd
import biogeme.database as db
import biogeme.biogeme as bio
import biogeme.models as models
from biogeme.expressions import Beta, DefineVariable,log

# Read the data
df = pd.read_csv("swissmetro.dat",sep='\t')
database = db.Database("swissmetro",df)

# The Pandas data structure is available as database.data. Use all the
# Pandas functions to invesigate the database
#print(database.data.describe())

# The following statement allows you to use the names of the variable
# as Python variable.
globals().update(database.variables)

# Removing some observations can be done directly using pandas.
#remove = (((database.data.PURPOSE != 1) & (database.data.PURPOSE != 3)) | (database.data.CHOICE == 0))
#database.data.drop(database.data[remove].index,inplace=True)

# Here we use the "biogeme" way for backward compatibility
exclude = (( PURPOSE != 1 ) * (  PURPOSE   !=  3  ) +  ( CHOICE == 0 )) > 0
database.remove(exclude)

# Parameters to be estimated
ASC_CAR = Beta('ASC_CAR',0,None,None,0)
ASC_TRAIN = Beta('ASC_TRAIN',0,None,None,0)
ASC_SM = Beta('ASC_SM',0,None,None,1)
B_TIME = Beta('B_TIME',0,None,0,0)
B_COST = Beta('B_COST',0,None,0,0)

# Definition of new variables
SM_COST =  SM_CO   * (  GA   ==  0  ) 
TRAIN_COST =  TRAIN_CO   * (  GA   ==  0  )

# Definition of new variables: adding columns to the database 
TRAIN_TT_SCALED = DefineVariable('TRAIN_TT_SCALED',\
                                 TRAIN_TT / 100.0,database)
TRAIN_COST_SCALED = DefineVariable('TRAIN_COST_SCALED',\
                                   TRAIN_COST / 100,database)
SM_TT_SCALED = DefineVariable('SM_TT_SCALED', SM_TT / 100.0,database)
SM_COST_SCALED = DefineVariable('SM_COST_SCALED', SM_COST / 100,database)
CAR_TT_SCALED = DefineVariable('CAR_TT_SCALED', CAR_TT / 100,database)
CAR_CO_SCALED = DefineVariable('CAR_CO_SCALED', CAR_CO / 100,database)

# Definition of the utility functions for latent class 1, where the
# time coefficient is zero
V11 = ASC_TRAIN + B_COST * TRAIN_COST_SCALED
V12 = ASC_SM + B_COST * SM_COST_SCALED
V13 = ASC_CAR + B_COST * CAR_CO_SCALED

# Associate utility functions with the numbering of alternatives
V1 = {1: V11,
      2: V12,
      3: V13}

# Definition of the utility functions for latent class 2, whete the
# time coefficient is estimated
V21 = ASC_TRAIN + B_TIME * TRAIN_TT_SCALED + B_COST * TRAIN_COST_SCALED
V22 = ASC_SM + B_TIME * SM_TT_SCALED + B_COST * SM_COST_SCALED
V23 = ASC_CAR + B_TIME * CAR_TT_SCALED + B_COST * CAR_CO_SCALED

# Associate utility functions with the numbering of alternatives
V2 = {1: V21,
      2: V22,
      3: V23}

# Associate the availability conditions with the alternatives
CAR_AV_SP =  DefineVariable('CAR_AV_SP',CAR_AV  * (  SP   !=  0  ),database)
TRAIN_AV_SP =  DefineVariable('TRAIN_AV_SP',TRAIN_AV  * (  SP   !=  0  ),database)
av = {1: TRAIN_AV_SP,
      2: SM_AV,
      3: CAR_AV_SP}

# Class membership model
W_OTHER = Beta('W_OTHER',0.5,0,1,0)
probClass1 = 1 - W_OTHER
probClass2 = W_OTHER

# The choice model is a discrete mixture of logit, with availability conditions
prob1 = models.logit(V1,av,CHOICE)
prob2 = models.logit(V2,av,CHOICE)
prob = probClass1 * prob1 + probClass2 * prob2
logprob = log(prob)

# Define level of verbosity
import biogeme.messaging as msg
logger = msg.bioMessage()
logger.setSilent()
#logger.setWarning()
#logger.setGeneral()
#logger.setDetailed()

# Create the Biogeme object
biogeme  = bio.BIOGEME(database,logprob)
biogeme.modelName = "07discreteMixture"

# Estimate the parameters
results = biogeme.estimate()
pandasResults = results.getEstimatedParameters()
print(pandasResults)