[英]How to make a 2d numpy array from an empty numpy array by adding 1d numpy arrays?
So I'm trying to start an empty numpy array with a = np.array([])
, but when i append other numpy arrays (like [1, 2, 3, 4, 5, 6, 7, 8]
and [9, 10, 11, 12, 13, 14, 15, 16]
to this array, then the result im basically getting is So I'm trying to start an empty numpy array with
a = np.array([])
, but when i append other numpy arrays (like [1, 2, 3, 4, 5, 6, 7, 8]
and [9, 10, 11, 12, 13, 14, 15, 16]
到这个数组,那么我基本上得到的结果是[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16]
. [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16]
。
But what i want as result is: [[1, 2, 3, 4, 5, 6, 7, 8], [9, 10, 11, 12, 13, 14, 15, 16]]
但我想要的结果是:
[[1, 2, 3, 4, 5, 6, 7, 8], [9, 10, 11, 12, 13, 14, 15, 16]]
IIUC you want to keep adding lists to your np.array. IIUC 你想继续向你的 np.array 添加列表。 In that case, you can use something like
np.vstack
to "append" the new lists to the array.在这种情况下,您可以使用类似
np.vstack
的东西将新列表“附加”到数组中。
a = np.array([[1, 2, 3],[4, 5, 6]])
np.vstack([a, [7, 8, 9]])
>>> array([[1, 2, 3],
[4, 5, 6],
[7, 8, 9]])
You can also use np.c_[]
, especially if a
and b
are already 1D arrays (but it also works with lists):您也可以使用
np.c_[]
,特别是如果a
和b
已经是一维 arrays (但它也适用于列表):
a = [1, 2, 3, 4, 5, 6, 7, 8]
b = [9, 10, 11, 12, 13, 14, 15, 16]
>>> np.c_[a, b]
array([[ 1, 9],
[ 2, 10],
[ 3, 11],
[ 4, 12],
[ 5, 13],
[ 6, 14],
[ 7, 15],
[ 8, 16]])
It also works "multiple times":它也可以“多次”工作:
>>> np.c_[np.c_[a, b], a, b]
array([[ 1, 9, 1, 9],
[ 2, 10, 2, 10],
[ 3, 11, 3, 11],
[ 4, 12, 4, 12],
[ 5, 13, 5, 13],
[ 6, 14, 6, 14],
[ 7, 15, 7, 15],
[ 8, 16, 8, 16]])
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