Python numpy.isposinf()用法及代碼示例

關於：
numpy.isposinf(array，y = None)：逐個測試是否為正無窮大，是否以布爾數組返回結果。

參數：

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.

代碼1：

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

輸出：

Positive: False 

Positive: False 

Positive: False 

Positive: True 

Positive: False 

Checking for positivity: [0 0 1]

代碼2：

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

輸出：

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

Is Positive Infifnity:
 [[False False False False False False]
 [False False False False False False]
 [False False False False False False]]

Is Positive Infifnity:
 [[ True]
 [False]]

參考文獻：
https://docs.scipy.org/doc/numpy-dev/reference/generated/numpy.isposinf.html#numpy.isposinf