numpy.ma.where()函数– Python

numpy.ma.where()函数返回一个掩码数组，其中包含来自 x 或 y 的元素，具体取决于条件。

Syntax : numpy.ma.where(condition, x, y)

Parameter :
condition : [array_like, bool] Where True, yield x, otherwise yield y.
x, y : [array_like, optional] Values from which to choose. x, y and condition need to be broadcastable to some shape.

Return : [MaskedArray] An masked array with masked elements where the condition is masked, elements from x where condition is True, and elements from y elsewhere.

代码#1：

# Python program explaining
# numpy.ma.where() function
   
# importing numpy as geek 
# and numpy.ma module as ma 
import numpy as geek 
import numpy.ma as ma
    
x = geek.ma.array(geek.arange(4.).reshape(2, 2), 
                        mask =[[0, 1], [1, 0]])
  
gfg = geek.ma.where(x > 5, x, -3.1416)
   
print (gfg)

输出 ：

[[-3.1416 --]
 [-- -3.1416]]

代码#2：

# Python program explaining
# numpy.ma.where() function
   
# importing numpy as geek 
# and numpy.ma module as ma 
import numpy as geek 
import numpy.ma as ma
    
x = geek.ma.array(geek.arange(9.).reshape(3, 3), 
       mask =[[0, 1, 0], [1, 0, 1], [0, 1, 0]])
  
gfg = geek.ma.where(x > 5, x, -3.1416)
   
print (gfg)

输出 ：

[[-3.1416 -- -3.1416]
 [-- -3.1416 --]
 [6.0 -- 8.0]]