skimage2.util.regular_grid

skimage2.util.regular_grid(ar_shape, n_points)

Find n_points regularly spaced along ar_shape.

The returned points (as slices) should be as close to cubically-spaced as possible. Essentially, the points are spaced by the Nth root of the input array size, where N is the number of dimensions. However, if an array dimension cannot fit a full step size, it is “discarded”, and the computation is done for only the remaining dimensions.

Parameters:

ar_shapearray_like of dtype int

The shape of the space embedding the grid. len(ar_shape) is the number of dimensions.

n_pointsint

The (approximate) number of points to embed in the space.

Returns:

slicestuple of (slice, …)

A slice along each dimension of ar_shape, such that the intersection of all the slices give the coordinates of regularly spaced points.

Changed in version 0.14.1: In scikit-image 0.14.1 and 0.15, the return type was changed from a list to a tuple to ensure compatibility with Numpy 1.15 and higher. If your code requires the returned result to be a list, you may convert the output of this function to a list with:

>>> result = list(regular_grid(ar_shape=(3, 20, 40), n_points=8))

Examples

>>> ar = np.zeros((20, 40))
>>> g = regular_grid(ar.shape, 8)
>>> g
(slice(5, None, 10), slice(5, None, 10))
>>> ar[g] = 1
>>> ar.sum()
8.0
>>> ar = np.zeros((20, 40))
>>> g = regular_grid(ar.shape, 32)
>>> g
(slice(2, None, 5), slice(2, None, 5))
>>> ar[g] = 1
>>> ar.sum()
32.0
>>> ar = np.zeros((3, 20, 40))
>>> g = regular_grid(ar.shape, 8)
>>> g
(slice(1, None, 3), slice(5, None, 10), slice(5, None, 10))
>>> ar[g] = 1
>>> ar.sum()
8.0