After wondering how human populations can increase in size and writing a simulator for the problem, a simpler question came to mind regarding a population without death. This creature population simulator is an old experiment that served its purpose well. The code here is committed for archival to be run under Python 2.5 or later versions.
Python, 93 lines
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Copy to clipboard1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 | def main():
while True:
creatures = get_creatures()
years = get_years()
summary = get_summary()
target = get_target()
simulate(creatures, years, summary, target)
if get_exit():
return
def get_creatures():
while True:
try:
creatures = int(raw_input('How many creatures do you want to start with? '))
if creatures > 0:
return creatures
print 'There must be at least one creature.'
except:
print 'You must enter a number.'
def get_years():
while True:
try:
years = int(raw_input('How many years do you want simulated? '))
if years > 0:
return years
print 'At least one year must be simulated.'
except:
print 'You must enter a number.'
def get_summary():
while True:
try:
answer = raw_input('Do you want a summary of the simulation? ').lower()
if answer == 'yes':
return True
if answer == 'no':
return False
except:
pass
print 'You must enter "yes" or "no".'
def get_target():
while True:
try:
target = int(raw_input('What is the target population (0 for None)? '))
if target > 0:
return target
return 0
except:
print 'You must enter a number.'
def simulate(creatures, years, summary, target):
print
divisions = [0 for division in range(21)]
divisions[20] = creatures
for year in range(years):
if not summary:
print 'It is year', year, 'and the divisions are as follows:'
print str(divisions)[1:-1]
children = divisions[20] / 2
divisions[20] += divisions[19]
for division in range(19):
divisions[19 - division] = divisions[18 - division]
divisions[0] = children
if target:
total = 0
for division in range(21):
total += divisions[division]
if total >= target:
break
print 'It is year', year + 1, 'and the divisions are as follows:'
print str(divisions)[1:-1]
total = 0
for division in range(21):
total += divisions[division]
print 'There are a total of', total, 'creatures.'
print
def get_exit():
while True:
try:
answer = raw_input('Do you wish to exit this program? ').lower()
if answer == 'yes':
return True
if answer == 'no':
return False
except:
pass
print 'You must enter "yes" or "no".'
if __name__ == '__main__':
main()
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