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>)

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().tolist()]
[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.