使用Python捕食者 - 獵物模擬。 Python閱讀方程有問題嗎？

Question

我正在做一個捕食獵物模擬，打印在一定時期內的獵物和捕食者的數量。

這是我第一次發佈，所以如果有任何問題，請讓我知道。

我在執行測試的信息是：

a= .1 
b= .01 
c= .01 
d= .00002 
prey_population = 1000 
predator_population = 20 
periods = 10 

a = float(input("Enter the rate at which prey birth exceeds natural death: ")) 
b = float(input("Enter the rate of predation: ")) 
c = float(input("Enter the rate at which predator deaths exceed births without food: ")) 
d = float(input("Predator increase with the presence of food: ")) 

prey_population = int(input("Enter prey population: ")) 
predator_population = int(input("Enter predator population: ")) 

periods = int(input("Enter the number of periods: ")) 

for i in range(1, periods + 1): 
    prey_population = int(prey_population * (1 + a - b * predator_population)) 
    predator_population = int(predator_population * (1 - c + d * prey_population)) 

    print("After period", i, "there are", predator_population, "predators") 
    print("After period", i, "there are", prey_population, "prey") 

我的信息是準確的獵物，直到第6期，我的捕食者輸出只精確到年第3期。

我的輸出是：

After period 1 there are 20 predators 
After period 1 there are 900 prey 

After period 2 there are 20 predators 
After period 2 there are 810 prey 

After period 3 there are 20 predators 
After period 3 there are 729 prey 

After period 4 there are 20 predators 
After period 4 there are 656 prey 

After period 5 there are 20 predators 
After period 5 there are 590 prey 

After period 6 there are 20 predators 
After period 6 there are 531 prey 

After period 7 there are 19 predators 
After period 7 there are 477 prey 

After period 8 there are 18 predators 
After period 8 there are 434 prey 

After period 9 there are 17 predators 
After period 9 there are 399 prey 

After period 10 there are 16 predators 
After period 10 there are 371 prey 

它應該顯示的數字是：

After period 1 there are 20 predators 
After period 1 there are 900 prey 

After period 2 there are 20 predators 
After period 2 there are 808 prey 

After period 3 there are 20 predators 
After period 3 there are 724 prey 

After period 4 there are 21 predators 
After period 4 there are 648 prey 

After period 5 there are 21 predators 
After period 5 there are 580 prey 

After period 6 there are 21 predators 
After period 6 there are 518 prey 

After period 7 there are 21 predators 
After period 7 there are 463 prey 

After period 8 there are 21 predators 
After period 8 there are 413 prey 

After period 9 there are 21 predators 
After period 9 there are 369 prey 

After period 10 there are 21 predators 
After period 10 there are 330 prey 

Answer 1

每回合你使用新的值來計算predator_population之前更新的prey_population值。這是拋棄結果。

Answer 2

我不認爲這有資格作爲一個答案，但它太長時間放在註釋，這樣"practicality beats purity"。

你問你的代碼做什麼，對於動輒就是：

的獵物新號碼等於：

• 老字號的獵物
  • 加這個回合的新胎（出生率*當前的獵物）（1）
  • 減去這個回合的殺死獵物[（捕食率*當前predato RS）*當前獵物] （1）
  • 圓這一切下來。

的大鱷新號碼等於：

• 老字號大鱷
  • 減去死亡（死亡率*當前的掠食者）的固定利率（ 1）
  • 加上「食品胎」 [（「食生」率*新號碼的獵物）*當前的掠食者] （1）
  • 圍繞這一切。

這是它應該做的？

（1）在這一點上新的號碼不被圓下來了

Answer 3

我發現這個問題，是的，它是四捨五入。方程中的整數是四捨五入的答案。我將其更改爲浮點數並在打印語句中四捨五入。我非常感謝大家的幫助。