Python numpy.isneginf()用法及代码示例

关于：
numpy.isneginf(array，y = None)：逐个测试是否为负无穷大，是否以布尔数组返回结果。

参数：

array:[array_like]Input array or object whose elements, we need to test for infinity.
y    :[array_like]A boolean array with the same shape and type as x to store the result.

返回：

boolean array containing the result. For scalar input, the result is a new boolean with value
True if the input is positive or negative infinity; otherwise the value is False.
For array input, the result is a boolean array with the same shape as the input and the values
are True where the corresponding element of the input is positive or negative infinity; 
elsewhere the values are False.

代码1：

# Python Program illustrating 
# numpy.isneginf() method 
   
import numpy as geek  
  
print("Negative:", geek.isneginf(1), "\n") 
  
print("Negative:", geek.isneginf(0), "\n") 
  
# not a number 
print("Negative:", geek.isneginf(geek.nan), "\n") 
  
#  infinity 
print("Negative:", geek.isneginf(geek.inf), "\n") 
  
print("Negative:", geek.isneginf(geek.NINF), "\n")  
  
x = geek.array([-geek.inf, 0., geek.inf]) 
y = geek.array([2, 2, 2]) 
print("Checking for negativity:", geek.isneginf(x, y)) 

输出：

Negative: False 

Negative: False 

Negative: False 

Negative: False 

Negative: True 

Checking for negativity: [1 0 0]

代码2：

# Python Program illustrating 
# numpy.isneginf() method 
    
import numpy as geek  
   
# Returns True/False value for each element  
b = geek.arange(18).reshape(3, 6) 
                 
print("\n",b) 
print("\nIs Negative Infifnity:\n", geek.isneginf(b)) 
  
# geek.inf :Positive Infinity 
# geek.NINF:negative Infinity 
b = [[geek.inf],  
     [geek.NINF]] 
print("\nIs Negative Infifnity:\n", geek.isneginf(b))

输出：

 [[ 0  1  2  3  4  5]
 [ 6  7  8  9 10 11]
 [12 13 14 15 16 17]]

Is Negative Infifnity:
 [[False False False False False False]
 [False False False False False False]
 [False False False False False False]]

Is Negative Infifnity:
 [[False]
 [ True]]

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