# numpy.indices¶

`numpy.``indices`(dimensions, dtype=<type 'int'>)[源代码]

Return an array representing the indices of a grid.

Compute an array where the subarrays contain index values 0,1,… varying only along the corresponding axis.

Parameters: dimensions : sequence of ints The shape of the grid. dtype : dtype, optional Data type of the result. grid : ndarray The array of grid indices, `grid.shape = (len(dimensions),) + tuple(dimensions)`.

Notes

The output shape is obtained by prepending the number of dimensions in front of the tuple of dimensions, i.e. if dimensions is a tuple `(r0, ..., rN-1)` of length `N`, the output shape is `(N,r0,...,rN-1)`.

The subarrays `grid[k]` contains the N-D array of indices along the `k-th` axis. Explicitly:

```grid[k,i0,i1,...,iN-1] = ik
```

Examples

```>>> grid = np.indices((2, 3))
>>> grid.shape
(2, 2, 3)
>>> grid        # row indices
array([[0, 0, 0],
[1, 1, 1]])
>>> grid        # column indices
array([[0, 1, 2],
[0, 1, 2]])
```

The indices can be used as an index into an array.

```>>> x = np.arange(20).reshape(5, 4)
>>> row, col = np.indices((2, 3))
>>> x[row, col]
array([[0, 1, 2],
[4, 5, 6]])
```

Note that it would be more straightforward in the above example to extract the required elements directly with `x[:2, :3]`.