Question

我有一个（3,3）numpy数组，想要找出绝对元素的符号值是最大值：

X = [[-2.1,  2,  3],
     [ 1, -6.1,  5],
     [ 0,  1,  1]]

s = numpy.argmax(numpy.abs(X),axis=0)

给出了我需要的元素的索引s = [ 0,1,1]。

如何使用此数组提取元素[ -2.1, -6.1, 5]以找出其符号？

Answer 1

试试这个：

# You might need to do this to get X as an ndarray (for example if X is a list)
X = numpy.asarray(X)

# Then you can simply do
X[s, [0, 1, 2]]

# Or more generally
X_argmax = X[s, numpy.arange(X.shape[1])]

Answer 2

部分答案：使用sign或signbit。

In [8]: x = numpy.array([-2.1, -6.1, 5])

In [9]: numpy.sign(x)
Out[9]: array([-1., -1.,  1.])

In [10]: numpy.signbit(x)
Out[10]: array([ True,  True, False], dtype=bool)

从numpy.argmax结果中提取numpy数组切片

2 个答案: