加权平均np.average()

定义：若有n个数  的权分别是 ，那么 

叫做这n个数的加权平均值。如果权重相同，加权平均值即为平均值

def weighted_average(datalist,weigth=1):
    numerator=0
    if weigth !=1:
        denominator=sum(weigth)
        assert len(datalist) == len(weigth), "length not equal"
        for i in range(len(datalist)):
            numerator+=datalist[i]*weigth[i]
    else:
        denominator = len(datalist)
        numerator=sum(datalist)
    return numerator/denominator


if __name__=='__main__':
    datalist=list(range(1,11))
    weigth=list(range(10,0,-1))
    num=weighted_average(datalist,weigth)
    print(num)