英文:
Numpy. How to split 2D array to multiple arrays by grid?
问题
我有一个numpy的二维数组：
c = np.arange(36).reshape(6, 6)
[[ 0, 1, 2, 3, 4, 5],
[ 6, 7, 8, 9, 10, 11],
[12, 13, 14, 15, 16, 17],
[18, 19, 20, 21, 22, 23],
[24, 25, 26, 27, 28, 29],
[30, 31, 32, 33, 34, 35]]
我想要按3x3的网格将它拆分成多个二维数组（就像将大图像按3x3的网格拆分为9个小图像）：
[[ 0, 1,| 2, 3,| 4, 5],
[ 6, 7,| 8, 9,| 10, 11],
---------+--------+---------
[12, 13,| 14, 15,| 16, 17],
[18, 19,| 20, 21,| 22, 23],
---------+--------+---------
[24, 25,| 26, 27,| 28, 29],
[30, 31,| 32, 33,| 34, 35]]
最后，我需要一个包含9个二维数组的数组，如下所示：
[[[0, 1], [6, 7]],
[[2, 3], [8, 9]],
[[4, 5], [10, 11]],
[[12, 13], [18, 19]],
[[14, 15], [20, 21]],
[[16, 17], [22, 23]],
[[24, 25], [30, 31]],
[[26, 27], [32, 33]],
[[28, 29], [34, 35]]]
这只是我需要的一个示例。我想知道如何通过网格（N，M）从大的二维数组中制作小的二维数组。
英文:
I have a numpy 2D-array:
c = np.arange(36).reshape(6, 6)
[[ 0, 1, 2, 3, 4, 5],
[ 6, 7, 8, 9, 10, 11],
[12, 13, 14, 15, 16, 17],
[18, 19, 20, 21, 22, 23],
[24, 25, 26, 27, 28, 29],
[30, 31, 32, 33, 34, 35]]
I want to split it to multiple 2D-arrays by grid 3x3. (It's like a split big image to 9 small images by grid 3x3):
[[ 0, 1,| 2, 3,| 4, 5],
[ 6, 7,| 8, 9,| 10, 11],
---------+--------+---------
[12, 13,| 14, 15,| 16, 17],
[18, 19,| 20, 21,| 22, 23],
---------+--------+---------
[24, 25,| 26, 27,| 28, 29],
[30, 31,| 32, 33,| 34, 35]]
At final i need array with 9 2D-arrays. Like this:
[[[0, 1], [6, 7]],
[[2, 3], [8, 9]],
[[4, 5], [10, 11]],
[[12, 13], [18, 19]],
[[14, 15], [20, 21]],
[[16, 17], [22, 23]],
[[24, 25], [30, 31]],
[[26, 27], [32, 33]],
[[28, 29], [34, 35]]]
It's just a sample what i need. I want to know how to make small 2D arrays from big 2D array by grid (N,M)
答案1
得分: 2
可以使用类似以下的方法：
```python
from numpy.lib.stride_tricks import sliding_window_view
out = np.vstack(sliding_window_view(c, (2, 2))[::2, ::2])
输出：
>>> out.tolist()
[[[0, 1], [6, 7]],
[[2, 3], [8, 9]],
[[4, 5], [10, 11]],
[[12, 13], [18, 19]],
[[14, 15], [20, 21]],
[[16, 17], [22, 23]],
[[24, 25], [30, 31]],
[[26, 27], [32, 33]],
[[28, 29], [34, 35]]]
<details>
<summary>英文:</summary>
You can use something like:
from numpy.lib.stride_tricks import sliding_window_view
out = np.vstack(sliding_window_view(c, (2, 2))[::2, ::2])
Output:
>>> out.tolist()
[[[0, 1], [6, 7]],
[[2, 3], [8, 9]],
[[4, 5], [10, 11]],
[[12, 13], [18, 19]],
[[14, 15], [20, 21]],
[[16, 17], [22, 23]],
[[24, 25], [30, 31]],
[[26, 27], [32, 33]],
[[28, 29], [34, 35]]]
</details>
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