Python numpy.extract()用法及代码示例

numpy.extract(条件，数组)：如果满足某些指定条件，则返回input_array的元素。
参数：

array     : Input array. User apply conditions on input_array elements
condition : [array_like]Condition on the basis of which user extract elements. 
      Applying condition on input_array, if we print condition, it will return an array
      filled with either True or False. Array elements are extracted from the Indices having 
      True value.

返回值：

Array elements that satisfy the condition.

# Python Program illustrating 
# numpy.compress method 
  
import numpy as geek 
  
array = geek.arange(10).reshape(5, 2) 
print("Original array : \n", array) 
  
a = geek.mod(array, 4) !=0
# This will show element status of satisfying condition 
print("\nArray Condition a : \n", a) 
  
# This will return elements that satisy condition "a" condition 
print("\nElements that satisfy condition a  : \n", geek.extract(a, array)) 
  
  
  
b = array - 4 == 1
# This will show element status of satisfying condition 
print("\nArray Condition b : \n", b) 
  
# This will return elements that satisy condition "b" condition 
print("\nElements that satisfy condition b  : \n", geek.extract(b, array))

输出：

Original array : 
 [[0 1]
 [2 3]
 [4 5]
 [6 7]
 [8 9]]

Array Condition a : 
 [[False  True]
 [ True  True]
 [False  True]
 [ True  True]
 [False  True]]

Elements that satisfy condition a  : 
 [1 2 3 5 6 7 9]

Array Condition b : 
 [[False False]
 [False False]
 [False  True]
 [False False]
 [False False]]

Elements that satisfy condition b  : 
 [5]