Hi John and others,
sorry about my etiquette errors. As you can tell I'm a newbie, and
appreciate all the help I can get. I'm trying to master this thing
with only the net and a couple of books as tutors.
Here is what I'm running at the interactive prompt:
>>> import myBDM
>>> L=[[100,'NA']]
>>> myBDM.evolve(L,100000)
Ideally, I'd like to bump it up to myBDM.evolve(L,10000000). L keeps
track of the number of subpopulations, how many individuals are in
each subpopulation, and the parent subpopulation each subpopulation
arose from.
Here is my code again:
import random
n=100
def evolve(L,limit):
"""
evolves the population until the population size reaches limit, by
choosing an individual of a particular subpopulation
type, then randomly performing
a birth, death, or mutation on this individual
"""
global n
while n<limit:
evnt = event()
if evnt!="None":
ind = chooseInd(L,n)
action(evnt,L,ind)
def chooseInd(L,n):
"""
randomly choose one subpopulation L[i] , so that the distribution
of choices is proportional to the values of L[i][0]
"""
choiceSum=0
index=0
choice = random.randint(1,n)
while choiceSum < choice:
choiceSum+=L[index][0]
index +=1
return (index-1)
def event():
"""
randomly chooses a birth (prob .3), death (prob .1) or mutation
(prob .1) event
"""
choice = random.random()
if choice <= .3:
event='b'
elif choice <= .4:
event ='d'
elif choice<= .5:
event = 'm'
else:
event = 'None'
return event
def action(event, L, index):
"""
decides what happens to the population/subpopulation, based on
whether
the event is a birth, death or mutation
"""
global n
if event == 'b':
L[index][0]+=1
n +=1
elif event == 'd':
L[index][0]-=1
n -=1
elif event == 'm':
L.append([1,index])
n +=1
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