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Python numpy.nanargmin()用法及代码示例


numpy.nanargmin(array,axis = None):返回忽略NaN的特定轴上数组的min元素的索引。
如果切片仅包含NaN和Inf,则结果将不可信任。
参数:

array : Input array to work on 
axis  : [int, optional]Along a specified axis like 0 or 1

返回:

Array of indices into the array with same shape as array.shape.
 with the dimension along axis removed.

代码1:


# Python Program illustrating 
# working of nanargmin() 
  
import numpy as geek  
  
# Working on 1D array 
array = [geek.nan, 4, 2, 3, 1] 
print("INPUT ARRAY 1 : \n", array) 
  
array2 = geek.array([[geek.nan, 4], [1, 3]]) 
  
# returning Indices of the min element 
# as per the indices ingnoring NaN 
print("\nIndices of min in array1 : ", geek.nanargmin(array)) 
  
# Working on 2D array 
print("\nINPUT ARRAY 2 : \n", array2) 
print("\nIndices of min in array2 : ", geek.nanargmin(array2)) 
  
print("\nIndices at axis 1 of array2 : ", geek.nanargmin(array2, axis = 1))

输出:

INPUT ARRAY 1 : 
 [nan, 4, 2, 3, 1]

Indices of min in array1 :  4

INPUT ARRAY 2 : 
 [[ nan   4.]
 [  1.   3.]]

Indices of min in array2 :  2

Indices at axis 1 of array2 :  [1 0]

代码2:比较argmin和nanargmin的工作

# Python Program illustarting 
# working of nanargmin() 
  
import numpy as geek  
  
# Working on 2D array 
array = ( [[ 8, 13, 5, 0], 
           [ geek.nan, geek.nan, 5, 3], 
           [10, 7, 15, 15], 
           [3, 11, 4, 12]]) 
print("INPUT ARRAY : \n", array) 
  
# returning Indices of the min element 
# as per the indices  
  
'''    
   [[ 8 13  5  0] 
   [ 0  2  5  3] 
   [10  7 15 15] 
   [ 3 11  4 12]] 
     ^  ^  ^  ^ 
     0  2  4  0  - element 
     1  1  3  0  - indices 
'''
  
print("\nIndices of min using argmin : ", geek.argmin(array, axis = 0)) 
print("\nIndices of min using nanargmin :  : ", geek.nanargmin(array, axis = 0))

输出:

INPUT ARRAY : 
 [[ 8 13  5  0]
 [ 0  2  5  3]
 [10  7 15 15]
 [ 3 11  4 12]]

Indices of min element :  [1 1 3 0]

参考文献:
https://docs.scipy.org/doc/numpy-dev/reference/generated/numpy.nanargmin.html



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