python语言程序设计9.1 计算平均值,标准差,中位数

from math import sqrt
def getNum():
    nums=[]
    iNumStr=input("输入数字(回车退出):")
    while iNumStr !="":
        nums.append(eval(iNumStr))
        iNumStr=input("输入数字(回车退出):")
    return nums
def mean(numbers):
    s=0.0
    for num in numbers:
        s=s+num
    return s/len(numbers)
def dev(numbers,mean):
    sdev=0.0
    for num in numbers:
        sdev= sdev+(num-mean)**2
    return sqrt(sdev/(len(numbers)-1))
def median(numbers):
    sorted(numbers)
    size=len(numbers)
    if size %2==0:
        med =(numbers[size//2-1]+numbers[size//2])/2
    else:
        med=numbers[size//2]
    return med
n=getNum()
m=mean(n)
print("平均值:{},方差:{:.2},中位数:{}.".format(m,dev(n,m),median(n)))

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