Python中的 numpy.median()

numpy.median(arr, axis = None) ：计算给定数据（数组元素）沿指定轴的中位数。

如何计算中位数？

• 给定数据点。
• 按升序排列它们
• 中位数 = 中期，如果总数没有。的条款是奇怪的。
• 中位数 = 中间项的平均值（如果总项数是偶数）

Parameters :
arr : [array_like]input array.
axis : [int or tuples of int]axis along which we want to calculate the median. Otherwise, it will consider arr to be flattened(works on all the axis). axis = 0 means along the column and axis = 1 means working along the row.
out : [ndarray, optional] Different array in which we want to place the result. The array must have the same dimensions as expected output.
dtype : [data-type, optional]Type we desire while computing median.

Results : Median of the array (a scalar value if axis is none) or array with median values along specified axis.

代码#1：

# Python Program illustrating 
# numpy.median() method 
    
import numpy as np
    
# 1D array 
arr = [20, 2, 7, 1, 34]
  
print("arr : ", arr) 
print("median of arr : ", np.median(arr))
   

输出 ：

arr :  [20, 2, 7, 1, 34]
median of arr :  7.0

代码#2：

# Python Program illustrating 
# numpy.median() method  
import numpy as np
    
# 2D array 
arr = [[14, 17, 12, 33, 44],  
       [15, 6, 27, 8, 19], 
       [23, 2, 54, 1, 4, ]] 
    
# median of the flattened array 
print("\nmedian of arr, axis = None : ", np.median(arr)) 
    
# median along the axis = 0 
print("\nmedian of arr, axis = 0 : ", np.median(arr, axis = 0)) 
   
# median along the axis = 1 
print("\nmedian of arr, axis = 1 : ", np.median(arr, axis = 1))
  
out_arr = np.arange(3)
print("\nout_arr : ", out_arr) 
print("median of arr, axis = 1 : ", 
      np.median(arr, axis = 1, out = out_arr))

输出 ：

median of arr, axis = None :  15.0

median of arr, axis = 0 :  [15.  6. 27.  8. 19.]

median of arr, axis = 1 :  [17. 15.  4.]

out_arr :  [0 1 2]
median of arr, axis = 1 :  [17 15  4]