Python Numpy 逆掩码
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Numpy inverse mask
提问by ustroetz
I want to inverse the true/false value in my numpy masked array.
我想反转我的 numpy 掩码数组中的真/假值。
So in the example below i don't want to mask out the second value in the data array, I want to mask out the first and third value.
所以在下面的例子中，我不想屏蔽数据数组中的第二个值，我想屏蔽掉第一个和第三个值。
Below is just an example. My masked array is created by a longer process than runs before. So I can not change the mask array itself. Is there another way to inverse the values?
下面只是一个例子。我的掩码数组是由比以前更长的过程创建的。所以我不能改变掩码数组本身。还有另一种方法可以反转值吗？
import numpy
data = numpy.array([[ 1, 2, 5 ]])
mask = numpy.array([[0,1,0]])
numpy.ma.masked_array(data, mask)
采纳答案by Joran Beasley
import numpy
data = numpy.array([[ 1, 2, 5 ]])
mask = numpy.array([[0,1,0]])
numpy.ma.masked_array(data, ~mask) #note this probably wont work right for non-boolean (T/F) values
#or
numpy.ma.masked_array(data, numpy.logical_not(mask))
for example
例如
>>> a = numpy.array([False,True,False])
>>> ~a
array([ True, False, True], dtype=bool)
>>> numpy.logical_not(a)
array([ True, False, True], dtype=bool)
>>> a = numpy.array([0,1,0])
>>> ~a
array([-1, -2, -1])
>>> numpy.logical_not(a)
array([ True, False, True], dtype=bool)
回答by Safi
Latest Python version also support '~' character as 'logical_not'. For Example
最新的 Python 版本也支持 '~' 字符作为 'logical_not'。例如
import numpy
data = numpy.array([[ 1, 2, 5 ]])
mask = numpy.array([[False,True,False]])
result = data[~mask]
