Python统计 |均值（）函数

先决条件：统计函数简介
在数据分析和统计方面， Python是一种非常流行的语言。幸运的是，Python3 提供了统计模块，它带有非常有用的函数，如 mean()、median()、mode() 等。
mean()函数可用于计算给定数字列表的平均值/平均值。它返回作为参数传递的数据集的平均值。
算术平均值是数据的总和除以数据点的数量。它是在一组范围内变化的值中对数据中心位置的度量。在Python中，我们通常通过将给定数字的总和除以存在的数字计数来做到这一点。

Given set of numbers : [n1, n2, n3, n5, n6]

Sum of data-set = (n1 + n2 + n3 + n4 + n5)
Number of data produced = 5

Average or arithmetic mean  = (n1 + n2 + n3 + n4 + n5) / 5

Syntax : mean([data-set])
Parameters : 
[data-set] : List or tuple of a set of numbers.
Returns : Sample arithmetic mean of the provided data-set.
Exceptions : 
TypeError when anything other than numeric values are passed as parameter. 
 

代码#1：工作

Python3

# Python program to demonstrate mean()
# function from the statistics module
 
# Importing the statistics module
import statistics
 
# list of positive integer numbers
data1 = [1, 3, 4, 5, 7, 9, 2]
 
x = statistics.mean(data1)
 
# Printing the mean
print("Mean is :", x)

输出 ：

Mean is : 4.428571428571429

代码 #2：工作

Python3

# Python program to demonstrate mean()
# function from the statistics module
 
# Importing the statistics module
from statistics import mean
 
# Importing fractions module as fr
# Enables to calculate mean of a
# set in Fraction
from fractions import Fraction as fr
 
 
# tuple of positive integer numbers
data1 = (11, 3, 4, 5, 7, 9, 2)
 
# tuple of a negative set of integers
data2 = (-1, -2, -4, -7, -12, -19)
 
# tuple of mixed range of numbers
data3 = (-1, -13, -6, 4, 5, 19, 9)
 
# tuple of a set of fractional numbers
data4 = (fr(1, 2), fr(44, 12), fr(10, 3), fr(2, 3))
 
# dictionary of a set of values
# Only the keys are taken in
# consideration by mean()
data5 = {1:"one", 2:"two", 3:"three"}
 
 
# Printing the mean of above datasets
print("Mean of data set 1 is % s" % (mean(data1)))
print("Mean of data set 2 is % s" % (mean(data2)))
print("Mean of data set 3 is % s" % (mean(data3)))
print("Mean of data set 4 is % s" % (mean(data4)))
print("Mean of data set 5 is % s" % (mean(data5)))

输出 ：

Mean of data set 1 is 5.857142857142857
Mean of data set 2 is -7.5
Mean of data set 3 is 2.4285714285714284
Mean of data set 4 is 49/24
Mean of data set 5 is 2

代码#3：类型错误

Python3

# Python3 code to demonstrate TypeError
 
# importing statistics module
from statistics import mean
 
# While using dictionaries, only keys are
# taken into consideration by mean()
dic = {"one":1, "three":3, "seven":7,
       "twenty":20, "nine":9, "six":6}
 
# Will raise TypeError
print(mean(dic))

输出 ：

Traceback (most recent call last):
  File "/home/9f8a941703745a24ddce5b5f6f211e6f.py", line 29, in 
    print(mean(dic))
  File "/usr/lib/python3.5/statistics.py", line 331, in mean
    T, total, count = _sum(data)
  File "/usr/lib/python3.5/statistics.py", line 161, in _sum
    for n, d in map(_exact_ratio, values):
  File "/usr/lib/python3.5/statistics.py", line 247, in _exact_ratio
    raise TypeError(msg.format(type(x).__name__))
TypeError: can't convert type 'str' to numerator/denominator

应用：
平均值/算术平均值是非常重要的函数之一，同时处理统计数据和大值。因此，使用 mean() 之类的函数，可以从大型数据集中提取趋势值和特征值。