如何使用多个索引从NumPy数组中获取值

I have a NumPy array that looks like this:

我有一个看起来像这样的NumPy数组：

arr = [100.10, 200.42, 4.14, 89.00, 34.55, 1.12]

How can I get multiple values from this array by index:

如何通过索引从此数组中获取多个值：

For example, how can I get the values at the index positions 1, 4, and 5?

例如，如何获取索引位置1,4和5的值？

I was trying something like this, which is incorrect:

我正在尝试这样的事情，这是不正确的：

arr[1, 4, 5]

3 个解决方案

#1

Try like this:

试试这样：

>>> arr = np.array([100.10, 200.42, 4.14, 89.00, 34.55, 1.12])
>>> arr[[1,4,5]]
array([ 200.42,   34.55,    1.12])

And for multidimensional arrays:

对于多维数组：

>>> arr = np.arange(9).reshape(3,3)
>>> arr
array([[0, 1, 2],
       [3, 4, 5],
       [6, 7, 8]])
>>> arr[[0, 1, 1], [1, 0, 2]]
array([1, 3, 5])

#2

you were close

你很亲密

>>> print arr[[1,4,5]]
[ 200.42   34.55    1.12]

#3

Another solution is to use np.take as specified in https://docs.scipy.org/doc/numpy-1.13.0/reference/generated/numpy.take.html

另一种解决方案是使用https://docs.scipy.org/doc/numpy-1.13.0/reference/generated/numpy.take.html中指定的np.take。

a = [4, 3, 5, 7, 6, 8]
indices = [0, 1, 4]
np.take(a, indices)
# array([4, 3, 6])