Question

我正在进行捕食者猎物模拟，在一定时期内打出猎物和食肉动物的数量。

这是我第一次发帖，如果有任何问题请告诉我。

我正在实施的测试信息是：

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")

我的信息对猎物来说是准确的，直到第6个时期，我的捕食者输出只准确到第3个时期。

我的输出是：

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

它应该显示的数字是：

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

在使用新值计算prey_population之前，每次转弯都会更新predator_population的值。这就是结果。

Answer 2

我发现了问题，是的，它正在四舍五入。等式中的int是四舍五入的答案。我将它更改为浮动并在print语句中舍入。我非常感谢大家的帮助。

Answer 3

我不认为这有资格作为答案，但要评论的时间太长，所以"practicality beats purity"。

您要求代码执行的操作是：

猎物的新数量等于：

旧的猎物数量
- 加上此回合的新生儿（出生率*现有猎物）（1）
- 减去此回合被杀死的猎物[（捕食率*当前捕食者）*当前捕食者] （1）
- 将这一切都打倒了。

捕食者的新数量等于：

旧的掠食者数量
- 减去固定死亡率（死亡率*当前捕食者）（1）
- 加上“食物分娩”[（“食物分娩率”*新数量的猎物）*当前的食肉动物] （1）
- 围绕这一切。

这是它应该做的吗？

（1）此时新号码尚未向下舍入

使用Python的捕食者 - 猎物模拟。 Python读取方程式的问题是错误的？

3 个答案: