捕食者vs獵物蟒蛇程序

Question

我必須找到捕食者對獵物示例的新值。

這是我當前的代碼

# 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) 

我現在的問題是，我對我的回答期數總是5.我需要它像1,2,3,4,5。目前，它看起來像 這裏{20}天敵和{700}獵物一段時間後{5.000000}

有{20}天敵和{489}獵物後時間段{5.000000}

有{ 20}天敵和{341}獵物時間段{之後5.000000}

有{20}天敵和時間段{5.000000}

有{20}天敵和{166}獵物後{238}獵物經過一段時間{5.000000}

任何想法如何解決？

Answer 1

您不改變popPrey以及popPred等你在每個itteration相同的輸出。 應該修正案（無prey，pred但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);