python - 捕食者vs猎物python程序

我必须为捕食者与猎物示例找到新的值。

这是我当前的代码

# Prompting user for all the inputs
A = float(input('Rate at which prey birth exceeds natural death'))
B = float(input('Rate of predation'))
C = float(input('Rate at which predator deaths exceed births without food'))
D = float(input('predator increase in the presence of food'))
popPrey = int(input('initial prey population'))
popPred = int(input('initial predator population'))
period = int(input('number of periods'))

# Finding new values of predator and prey populations
for i in range(period):
    popPrey, popPred = popPrey*(1+A-B*popPred), popPred*(1-C+D*popPrey)
    print "There are {%.0f} predators and {%.0f} prey after time period {%f}" %(popPred,popPrey,period)

我现在的问题是我回答的周期数始终为5。我需要使其与1,2,3,4,5相似。目前看起来像
在{5.000000}时间段之后，这里有{20}个捕食者和{700}个猎物

时间段{5.000000}之后有{20}个捕食者和{489}个猎物

在时间段{5.000000}之后，有{20}个捕食者和{341}个猎物

时间段{5.000000}之后有{20}个捕食者和{238}个猎物

时间段{5.000000}之后有{20}个捕食者和{166}个猎物

有什么想法可以解决吗？

最佳答案

您无需更改popPrey以及popPred，因此每次触发时具有相同的输出。
假设的修正案（不是prey，pred，而是popPrey，popPred）：

 for i in range(period):
   # popPrey and popPred is a function of popPrey and popPred
   popPrey, popPred = popPrey*(1+A-B*popPred), popPred*(1-C+D*popPrey)
   print "There are {%.0f} predators and {%.0f} prey after time period {%f}" %(popPred,popPrey,i);