[Tutor] migration simulation

[Joshua Pollack]

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Hi all,

There's been some talk of simulation stuff using python lately, and I 
thought I'd pose a question I had.  I'm super new to python and 
programming general
so this isn't particularly noteworthy but...

I've a migration simulation that's part of a bigger drift and selection 
model.  In the migration section, I define a population as being made of
subpopulations and then pop out migrants from the subpops at a given 
probability.  The migrants then get re-inserted into subpops randomly.
It's all very simple except I'm having a problem with back migration. 
 Migrants will sometimes migrate back to their original population. 
 Does anyone know of a
a way to tag each migrant so that I can make sure they don't 
back-migrate?  See attached code.

Thanks so much!!

Joshua Pollack

P.S. -f this gets sent twice, please ignore message #2.  Thanks again.






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## Migration Simulation
import random

## Create subpopulations
sf=[0]*5+[1]*5
la=[2]*5+[3]*5
biloxi=[4]*5+[5]*5
migrants=[]

## Join subpops into single pop
all=[sf,la,biloxi]
print "pre-migrate:", all

## Pull out migrants at a probability of 5%
for i in all:
    for j in i:
        if random.random()<=.05:
            migrants.append(i.pop(j))

## Drop migrants back into random subpopulations    
for i in migrants:
    random.choice(all).append(i)
print "post-migrate:", all




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