array_split.ShapeSplitter¶

class array_split.ShapeSplitter(array_shape, indices_or_sections=None, axis=None, array_start=None, array_itemsize=1, tile_shape=None, max_tile_bytes=None, max_tile_shape=None, sub_tile_shape=None, halo=None, tile_bounds_policy=<property object>)[source]¶

Implements array shape splitting. There are three main (top-level) methods:

__init__()

Initialisation of parameters which define the split.

set_split_extents()

Calculates the per-axis indices for the cuts. Sets the split_shape, split_begs and split_ends attributes.

calculate_split()

Calls set_split_extents() followed by calculate_split_from_extents() to return the numpy.ndarray of tuple elements (slices).

Example:

>>> import numpy as np
>>> ary = np.arange(0, 10)
>>> splitter = ShapeSplitter(ary.shape, 3)
>>> split = splitter.calculate_split()
>>> split.shape
(3,)
>>> split
array([(slice(0, 4, None),), (slice(4, 7, None),), (slice(7, 10, None),)],
      dtype=[('0', 'O')])
>>> [ary[slyce] for slyce in split.flatten()]
[array([0, 1, 2, 3]), array([4, 5, 6]), array([7, 8, 9])]
>>>
>>> splitter.split_shape # equivalent to split.shape above
array([3])
>>> splitter.split_begs  # start indices for tile extents
[array([0, 4, 7])]
>>> splitter.split_ends  # stop indices for tile extents
[array([ 4,  7, 10])]

Methods

`__init__`(array_shape[, indices_or_sections, ...])	Initialises parameters which define a split.
`calculate_axis_split_extents`(num_sections, size)	Divides `range(0, size)` into (approximately) equal sized intervals.
`calculate_split`()	Computes the split.
`calculate_split_by_indices_per_axis`()	Returns split calculated using extents obtained from `indices_per_axis`.
`calculate_split_by_split_size`()	Returns split calculated using extents obtained from `split_size` and `split_num_slices_per_axis`.
`calculate_split_by_tile_max_bytes`()	Returns split calculated using extents obtained from `max_tile_bytes` (and `max_tile_shape`, `sub_tile_shape`, `halo`).
`calculate_split_by_tile_shape`()	Returns split calculated using extents obtained from `tile_shape`.
`calculate_split_from_extents`()	Returns split calculated using extents obtained from `split_begs` and `split_ends`.
`calculate_split_halos_from_extents`()	Returns `(self.ndim, 2)` shaped halo array elements indicating the halo for each split.
`check_consistent_parameter_dimensions`()	Ensure that all parameter dimensions are consistent with the `array_shape` dimension.
`check_consistent_parameter_grouping`()	Ensures this object does not have conflicting groups of parameters.
`check_split_parameters`()	Ensures this object has a state consistent with evaluating a split.
`check_tile_bounds_policy`()	Raises `ValueError` if `tile_bounds_policy` is not in `[self.ARRAY_BOUNDS, self.NO_BOUNDS]`.
`convert_halo_to_array_form`(halo)	Converts the `halo` argument to a `(self.array_shape.size, 2)` shaped array.
`set_split_extents`()	Sets split extents (`split_begs` and `split_ends`) calculated using selected attributes set from `__init__()`.
`set_split_extents_by_indices_per_axis`()	Sets split shape `split_shape` and split extents (`split_begs` and `split_ends`) from values in `indices_per_axis`.
`set_split_extents_by_split_size`()	Sets split shape `split_shape` and split extents (`split_begs` and `split_ends`) from values in `split_size` and `split_num_slices_per_axis`.
`set_split_extents_by_tile_max_bytes`()	Sets split extents (`split_begs` and `split_ends`) calculated using from `max_tile_bytes` (and `max_tile_shape`, `sub_tile_shape`, `halo`).
`set_split_extents_by_tile_shape`()	Sets split shape `split_shape` and split extents (`split_begs` and `split_ends`) from value of `tile_shape`.
`update_tile_extent_bounds`()	Updates the `tile_beg_min` and `tile_end_max` data members according to `tile_bounds_policy`.

Attributes

`array_itemsize`	The number of bytes per array element, see `max_tile_bytes`.
`array_shape`	The shape of the array which is to be split.
`array_start`	The start index.
`halo`	Per-axis -ve and +ve halo sizes for extending tiles to overlap with neighbouring tiles.
`indices_per_axis`	The per-axis indices indicating the cuts for the split.
`logger`	Class attribute for `logging.Logger` logging.
`max_tile_bytes`	The maximum number of bytes for any tile (including `halo`) in the returned split.
`max_tile_shape`	Per-axis maximum sizes for calculated tiles.
`split_begs`	The list of per-axis start indices for `slice` objects.
`split_ends`	The list of per-axis stop indices for `slice` objects.
`split_num_slices_per_axis`	Number of slices per axis.
`split_shape`	The shape of the calculated split array.
`split_size`	An `int` indicating the number of tiles in the calculated split.
`sub_tile_shape`	Calculated tile shape will be an integer multiple of this sub-tile shape.
`tile_beg_min`	The per-axis minimum index for `slice.start`.
`tile_bounds_policy`	A string indicating whether tile halo extents can extend beyond the array domain.
`tile_end_max`	The per-axis maximum index for `slice.stop`.
`tile_shape`	The shape of all tiles in the calculated split.
`valid_tile_bounds_policies`	Class attribute indicating list of valid values for `tile_bound_policy`.