Python报错：'>' not supported between instances of 'NoneType' and 'NoneType'

Question

在计算空气质量指数AQI值，输入的是数字如：24 35，然后得出结果。但不知道哪里类型不对，运行不了，想请教一下应该怎么改。

def cal_pm_iaqi(pm_val):
    #计算PM2.5的IAQI
    if 0 <= pm_val < 36:
        iaqi = cal_linear(0, 50, 0, 35, pm_val)
    elif 36 <= pm_val < 76:
        iaqi = cal_linear(50, 100, 35, 75, pm_val)
    elif 76 <= pm_val < 116:
        iaqi = cal_linear(100, 150, 75, 115, pm_val)


def cal_co_iaqi(co_val):
    #计算CO的IAQI
    if 0 <= co_val < 3:
        iaqi = cal_linear(0, 50, 0, 2, co_val)
    elif 3 <= co_val < 5:
        iaqi = cal_linear(50, 100, 2, 4, co_val)
    elif 5 <= co_val < 15:
        iaqi = cal_linear(100, 150, 4, 14, co_val)

def cal_aqi(param_list):
    #AQI计算
    pm_val = param_list[0]
    co_val = param_list[1]

    pm_iaqi = cal_pm_iaqi(pm_val)
    co_iaqi = cal_co_iaqi(co_val)

    iaqi_list = []
    iaqi_list.append(pm_iaqi)
    iaqi_list.append(co_iaqi)

    aqi = max(iaqi_list)
    return aqi

def main():
    # 主函数
    print('请输入以下信息，用空格分开')
    input_str = (input('(1)PM2.5 (2)CO:'))
    str_list = input_str.split(' ')
    pm_val = int(str_list[0])
    co_val = int(str_list[1])

    param_list = []
    param_list.append(pm_val)
    param_list.append(co_val)

    #调用AQI计算函数
    aqi_val = cal_aqi(param_list)
    print('空气质量指数为：{}'.format(aqi_val))

# 按间距中的绿色按钮以运行脚本。
if __name__ == '__main__':
    main()

Answer 1

def cal_pm_iaqi(pm_val):
    #计算PM2.5的IAQI
    if 0 <= pm_val < 36:
        iaqi = cal_linear(0, 50, 0, 35, pm_val)
    elif 36 <= pm_val < 76:
        iaqi = cal_linear(50, 100, 35, 75, pm_val)
    elif 76 <= pm_val < 116:
        iaqi = cal_linear(100, 150, 75, 115, pm_val)
    return iaqi
 
 
def cal_co_iaqi(co_val):
    #计算CO的IAQI
    if 0 <= co_val < 3:
        iaqi = cal_linear(0, 50, 0, 2, co_val)
    elif 3 <= co_val < 5:
        iaqi = cal_linear(50, 100, 2, 4, co_val)
    elif 5 <= co_val < 15:
        iaqi = cal_linear(100, 150, 4, 14, co_val)
     return iaqi