##################################################################
# Implementation of a model of seal foraging behaviour
#
# Parameters shared by the other programs.
#
# Copyright (C) 2003 Greg Baker, Tony Wong, Alejandro Frid
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
# http://www.gnu.org/copyleft/gpl.html
#parameters last modified by Alejandro 12 June 03

from math import pow

#################################
# Model parameters

fitfile = "fitness.data"
decfile = "decision.data"

t_period = 10 # seconds--length of one time unit
e_unit = 1000.0 # kJ per energy unit
o_unit = 400.0 # mL per oxygen unit

#t_total = 1 * 24 * 60 * 60 # seconds--total length of the simulation (1 day)
t_total = 1000*t_period # seconds--total length of the simulation (1000 units)

tmax = t_total/t_period # time units--total time units in simulation
haul_time=int(6000/t_period) # time units--time needed to haul out/in
dive_time=int(100/t_period) # time units--time needed to dive up/down

xrep=6 # energy units
xmax=10 # energy units

yk=6 # oxygen units
ymax=10 # oxygen units

hmax=3 # number of habitats

basal=(0.971/e_unit) # energy units
swimming=2*basal # energy units
moving=(1.625/e_unit) # energy units
chasing=2*moving # energy units
max_o_gain=(40.425/o_unit) # oxygen units
base_o_gain=max_o_gain/4 # oxygen units
diving_o_cost=(80.85/o_unit) # oxygen units
chasing_o_cost=2*diving_o_cost # oxygen units

#enc prob: P(find food in bottom time of 2 min)=1, therefore for one unit it is 0.08
encounter_prob=0.08 # prob of encountering prey at depth
catch_prob=.40 # prob of catching prey if encountered
prey_gain=2087/e_unit # energy units--gain if prey caught

# probabilities of being depredated by a [sleeper shark, killer whale] ...
#haul_prob=[0,0] # ...in haulout/surface transit
#surf_prob=[0,0] # ...at the surface
#dive_prob=[0,0] # ...in surface/depth transit
#depth_prob=[0,0] # ...at depth

#june 18 corrected for sleeper shark analysis of iphc-lee data 
#then experiments
#haul is surface/2, dive is depth/4
haul_prob=[0.68e-8, 3.5e-5] # ...in haulout/surface transit
surf_prob=[1.36e-8, 7e-5] # ...at the surface
dive_prob=[0.395e-8, 2.8e-12] # ...in surface/depth transit
depth_prob=[1.58E-08, 2.8e-13] # ...at depth


def survive(p):
    """
    function used to combine two probabilies of depredation into prob.
    of survival
    TODO: check this vs. Clark's formula
    """
    return 1 - p[0] - p[1] + p[0]*p[1]


# import one of the numeric array modules (either will do)
try:
    from numarray import zeros, Float, Int8, fromfile
except:
    from Numeric import zeros, Float, Int8, fromfile


# survival probabilities in various situations.
# survive_prob[h,d] is the prob of survival in habitat h, decision d
survive_prob=zeros((hmax,hmax), Float)
survive_prob[0,0] = 1.0
survive_prob[0,1] = pow(survive(haul_prob), haul_time)
survive_prob[1,0] = pow(survive(haul_prob), haul_time)
survive_prob[1,1] = survive(surf_prob)
survive_prob[1,2] = pow(survive(dive_prob), dive_time)
survive_prob[2,1] = pow(survive(dive_prob), dive_time)
survive_prob[2,2] = survive(depth_prob)


impossible=-1 # the fitness if the seal tries to do impossible things