Python中的 numpy.isinf()

numpy.isinf()函数按元素测试它是 +ve 还是 -ve 无穷大，或者是否将结果作为布尔数组返回。

Syntax: numpy.isinf(array [, out])

参数 ：

array : [array_like]Input array or object whose 
         elements, we need to test for  infinity
out   : [ndarray, optional]Output array placed 
        with result. Its type is preserved and
        it  must be of the right shape to hold 
         the output.

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

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

输出 ：

Finite :  False 

Finite :  False 

Finite :  False 

Finite :  True 

Finite :  True 

Checking for infinity :  [1 0 1]

代码 2：

Python

# Python Program illustrating
# numpy.isinf() method
   
import numpy as geek
  
# Returns True/False value for each element
b = geek.arange(8).reshape(2, 4)
                
print("\n",b)
print("\nIs Infinity : \n", geek.isinf(b))
 
# geek.inf  : Positive Infinity
# geek.NINF : negative Infinity
b = [[geek.inf],
     [geek.NINF]]
print("\nIs Infinity : \n", geek.isinf(b))

输出 ：

[[0 1 2 3]
 [4 5 6 7]]

Is Infinity : 
 [[False False False False]
 [False False False False]]

Is Infinity : 
 [[ True]
 [ True]]

参考 ：
https://docs.scipy.org/doc/numpy-dev/reference/generated/numpy.isinf.html#numpy.isinf