python求平均数、方差、中位数的例子

def getNum():       #获取用户不定长度的输入
  nums = []
  iNumStr = input("请输入数字(回车退出):")
  while iNumStr != "":
    nums.append(eval(iNumStr))
    iNumStr = input("请输入数学(回车退出):")
  return nums

def mean(numbers):     #计算平均值
  s = 0.0
  for num in numbers:
    s = s + num
  return s/len(numbers)

def dev(numbers, mean):  #计算方差
  sdev = 0.0
  for num in numbers:
    sdev = sdev + (num - mean)**2
  return pow(sdev / (len(numbers)-1), 0.5)

def median(numbers):    #计算中位数
  numbers = sorted(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)))