A Population of Fish There is a population of fish numbering 10000 at the start of the year. Every month 5% of the fish alive at the start of the month, excluding offspring, die during the month. For the months of May/June/July 25% of the fish alive at the start of the month pair off and pro-create. Each pair have 3 off-spring. Every month, 15% of newly born fish over 3 months old depart the colony. Assumptions: Off spring do not pro-create Make any other assumptions you need if you are in doubt. Write code to calculate the number of fish at the end of the year
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# Can't have partial fish. Ignore floats, make it an int.
alive = 10000
d={}
for i in range (0,12):
if i == 4 or i == 5 or i == 6:
# approximate 12.5%
procreate = alive/8
offspring = procreate*3
d["offspring{0}".format(i)]=offspring
if i > 7:
d['offspring4'] = d['offspring4'] - d['offspring4']/100*15
if i > 8:
d['offspring5'] = d['offspring5'] - d['offspring5']/100*15
if i > 9:
d['offspring6'] = d['offspring6'] - d['offspring6']/100*15
dead = alive/20
alive = alive - dead
for i in d:
alive += d[i]
print (alive)
USE tempdb
DECLARE @fish FLOAT = 10000;
DECLARE @offSpring FLOAT = 0;
DECLARE @departed FLOAT = 0;
DECLARE @month INT = '1';
WITH fish (
fish
,offSpring
,leavers
,[month]
)
AS (
SELECT @fish AS fish
,@offSpring AS offSpring
,@departed AS leavers
,@month AS [month]
UNION ALL
SELECT ROUND(fish.fish - (fish.fish * 0.05), 0)
,fish.offSpring + CASE
WHEN fish.[month] IN (
1
,2
,3
,7
,8
,9
,10
,11
,12
)
THEN 0
ELSE ROUND(ROUND(ROUND(fish.fish - (fish.fish * 0.05), 0) * 0.125, 0) * 3, 0)
END
,fish.leavers + CASE
WHEN fish.[month] IN (
1
,2
,3
,4
,5
,6
)
THEN 0
ELSE ROUND(ROUND(ROUND(ROUND(fish.fish - (fish.fish * 0.05), 0) * 0.125, 0) * 3, 0) * 0.15, 0)
END AS leavers
,fish.[month] + 1 AS [month]
FROM fish
WHERE [month] < 13
)
--Select * from fish -- Array of fish*/
-- max val
SELECT (fish.fish + fish.offSpring) - fish.leavers AS colonysize
FROM fish
WHERE fish.[month] = 13;
from __future__ import division
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