问题

我从numpy得到了一个2D矩阵（np.zeros），我希望这个矩阵的每个元素都是一个具有2个元素的1D列表，这是我的代码：

```python
import numpy as np

N = 3
x = np.linspace(0, 10, N)
y = np.linspace(0, 10, N)

temp = np.zeros((N, N, 2))

for i in range(len(x)):
    for j in range(len(y)):
        temp[i, j] = [x[i], y[j]]

但是我得到了错误：

TypeError: float() argument must be a string or a real number, not 'list'

上述异常直接导致了以下异常：

Traceback (most recent call last):
  File (...), line 15, in <module>
    temp[i, j] = [x[i], y[j]]
ValueError: setting an array element with a sequence.

我理解了这个问题，但是不知道如何解决它。

<details>
<summary>英文:</summary>

I&#39;ve got a 2D matrix from numpy (np.zeros) and I would like that every element of this matrix is a 1D list with 2 elements, this is my code:

import numpy as np

N = 3
x = np.linspace(0,10,N)
y = np.linspace(0,10,N)

temp = np.zeros((N, N))

for i in range(len(x)):
for j in range(len(y)):
temp[i, j] = [x[i], y[j]]

but I've got error:

TypeError: float() argument must be a string or a real number, not 'list'

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
File (...), line 15, in <module>
temp[i, j] = [x[i], y[j]]
ValueError: setting an array element with a sequence.

And okay, I understand this problem, but I don't know how to solve it.

</details>


# 答案1
**得分**: 2

你可以在构建数组时设置`dtype=object`并存储列表，但这样效率较低。也可以定义自定义的dtype：

```python
import numpy as np

# 定义包含两个float64字段的自定义类型
pair_type = np.dtype("f8, f8")
x = np.zeros((3, 3), dtype=pair_type)
x[0, 0] = (1.5, 2.5)

你可以将x[i, j]检索为一个元组。

import numpy as np

# custom type of 2 float64 fields
pair_type = np.dtype("f8, f8")
x = np.zeros((3, 3), dtype=pair_type)
x[0, 0] = (1.5, 2.5)

答案2

得分: 0

以下是翻译好的部分：

使用numpy.meshgrid + numpy.stack，可以方便地获得您正在搜索的结果：

np.stack(np.meshgrid(x, y, indexing='ij'), axis=-1)

array([[[ 0.,  0.],
        [ 0.,  5.],
        [ 0., 10.]],

       [[ 5.,  0.],
        [ 5.,  5.],
        [ 5., 10.]],

       [[10.,  0.],
        [10.,  5.],
        [10., 10.]]])

np.stack(np.meshgrid(x, y, indexing='ij'), axis=-1)

array([[[ 0.,  0.],
        [ 0.,  5.],
        [ 0., 10.]],

       [[ 5.,  0.],
        [ 5.,  5.],
        [ 5., 10.]],

       [[10.,  0.],
        [10.,  5.],
        [10., 10.]]])