天气预测（晴天or雨天）

# 晴天walk
Psw = 0.6
Prw = 0.1
# 晴天shop
Pss = 0.3
Prs = 0.4
# 晴天clear
Psc = 0.1
Prc = 0.5
# 晴天转晴天
Ps_s = 0.6
# 晴天转阴天
Ps_r = 0.4
# 阴天转晴天
Pr_s = 0.3
# 阴天转阴天
Pr_r = 0.7


# 第一天下雨
def Rday1():
    prob = 0.6 * Prw
    return prob


# 第一天晴天
def Sday1():
    prob = 0.4 * Psw
    return prob


# 第二天雨天 购物
def Rday2(day1, probday1):
    # 第一天雨天转雨天
    if day1 == "r":
        prob = probday1 * Pr_r * Prs
    # 第一天晴天转雨天
    else:
        prob = probday1 * Ps_r * Prs
    return prob


# 第二天晴天
def Sday2(day1, probday1):
    # 第一天雨天转晴天
    if day1 == "r":
        prob = probday1 * Pr_s * Pss
    # 第一天晴天转晴天
    else:
        prob = probday1 * Ps_s * Pss
    return prob


# 第三天雨天清理
def Rday3(day2, probday2):
    # 第二天雨天转雨天
    if day2 == "r":
        prob = probday2 * Pr_r * Prc
    # 第二天晴天转雨天
    else:
        prob = probday2 * Ps_r * Prc
    return prob


# 第三天晴天
def Sday3(day2, probday2):
    # 第二天雨天转晴天
    if day2 == "r":
        prob = probday2 * Pr_s * Psc
    # 第二天晴天转晴天
    else:
        prob = probday2 * Ps_s * Psc
    return prob


# 第一天天气概率
S1 = Sday1()
R1 = Rday1()
print("第一天雨天概率：", R1)
print("第一天雨天概率：", S1)

SS2 = Sday2('s', S1)
RS2 = Sday2('r', R1)
S2 = SS2 + RS2
print("第二天晴天概率:", S2)

SR2 = Rday2('s', S1)
RR2 = Rday2('r', R1)
R2 = SR2 + RR2
print("第二天雨天概率:", R2)
SR3 = Rday3('s', S2)
RR3 = Rday3('r', R2)
R3 = SR3 + RR3
print("第三天雨天概率:", R3)
SS3 = Sday3('s', S2)
RS3 = Sday3('r', R2)
S3 = SS3 + RS3
print("第三天晴天概率:", S3)

print(max(R1, S1), max(R2, S2), max(R3, S3))  # 晴天 雨天 雨天

# print("SS2", SS2)
# print("RS2", RS2)
# print("SR2", SR2)
# print("RR2", RR2)
# print("SR2", SR3)
# print("RR2", RR3)
# print("SR2", SS3)
# print("RR2", RS3)

预测结果：

晴天 雨天 雨天

```# 第一天天气为1，第二天为2，第三天为3
# 输入前一天晴天、下雨概率，今天编号及天气，此天气下做某事概率
def predict(before_s_prob, before_r_prob, today, weather, do_something):
    global result
    if today == 1:
        if weather == 'r':
            result = 0.6 * do_something
        else:
            result = 0.4 * do_something
    else:
        if weather == 's':
            result = (before_r_prob * Pr_s + before_s_prob * Ps_s) * do_something
        elif weather == 'r':
            result = (before_r_prob * Pr_r + before_s_prob * Ps_r) * do_something

    return today, weather, result

# 晴天walk
Psw = 0.6
Prw = 0.1
# 晴天shop
Pss = 0.3
Prs = 0.4
# 晴天clear
Psc = 0.1
Prc = 0.5
# 晴天转晴天
Ps_s = 0.6
# 晴天转阴天
Ps_r = 0.4
# 阴天转晴天
Pr_s = 0.3
# 阴天转阴天
Pr_r = 0.7


# 第一天天气为1，第二天为2，第三天为3
# 输入前一天晴天、下雨概率，今天编号及天气，此天气下做某事概率
def predict(before_s_prob, before_r_prob, today, weather, do_something):
    global result
    if today == 1:
        if weather == 'r':
            result = 0.6 * do_something
        else:
            result = 0.4 * do_something
    else:
        if weather == 's':
            result = (before_r_prob * Pr_s + before_s_prob * Ps_s) * do_something
        elif weather == 'r':
            result = (before_r_prob * Pr_r + before_s_prob * Ps_r) * do_something

    return today, weather, result


if __name__ == '__main__':
    print("---------------测试案例 start-------------")
    Result = predict(0.24, 0.06, 2, "r", Prs)
    print("第{0}天是{1}的概率为{2}".format(Result[0], Result[1], Result[2]))
    print("---------------测试案例 end-------------")

    R1 = predict(0, 0, 1, "r", Prw)
    S1 = predict(0, 0, 1, "s", Psw)
    R2 = predict(0.24, 0.06, 2, "r", Prs)
    S2 = predict(0.24, 0.06, 2, "s", Pss)
    R3 = predict(0.0486, 0.0552, 3, "r", Prc)
    S3 = predict(0.0486, 0.0552, 3, "s", Psc)
    print(R1)
    print(S1)
    print(R2)
    print(S2)
    print(R3)
    print(S3)