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Break out all reformatting functions.
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@jakirkham
jakirkham committed Dec 8, 2016
1 parent 9105584 commit 708d9bc
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249 changes: 6 additions & 243 deletions kenjutsu/core.py
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Expand Up @@ -18,261 +18,24 @@
"""


from __future__ import absolute_import


__author__ = "John Kirkham <kirkhamj@janelia.hhmi.org>"
__date__ = "$Dec 08, 2016 11:35:58 GMT-0500$"


import collections
import itertools
import numbers
import operator
import math
import warnings

import kenjutsu.format

def reformat_slice(a_slice, a_length=None):
"""
Takes a slice and reformats it to fill in as many undefined values as
possible.
Args:
a_slice(slice): a slice to reformat.
a_length(int): a length to fill for stopping if not
provided.
Returns:
(slice): a new slice with as many values filled in as
possible.
Examples:
>>> reformat_slice(slice(2, -1, None))
slice(2, -1, 1)
>>> reformat_slice(slice(2, -1, None), 10)
slice(2, 9, 1)
"""

new_slice = a_slice
if (new_slice is Ellipsis) or (new_slice == tuple()):
new_slice = slice(None)
elif isinstance(a_slice, numbers.Integral):
if a_slice < 0:
new_slice = slice(a_slice, a_slice-1, -1)
else:
new_slice = slice(a_slice, a_slice+1, 1)
elif isinstance(a_slice, collections.Sequence):
if not all(map(lambda i: isinstance(i, numbers.Integral), a_slice)):
raise ValueError(
"Arbitrary sequences not permitted."
" All elements must be of integral type."
)

# Normalize each integer in the range.
new_slice = []
for i in a_slice:
new_slice.append(reformat_slice(i, a_length))
return new_slice
elif not isinstance(a_slice, slice):
raise ValueError(
"Expected a `slice` type. Instead got `%s`." % str(a_slice)
)

if new_slice.step == 0:
raise ValueError("Slice cannot have a step size of `0`.")

start = new_slice.start
stop = new_slice.stop
step = new_slice.step

# Fill unknown values.
if step is None:
step = 1
if start is None:
if step > 0:
start = 0
elif step < 0:
start = -1
if (stop is None) and (step > 0):
stop = a_length

stop_i = stop is not None

# Make adjustments for length
if a_length is not None:
# Normalize out-of-bound step sizes.
if step < -a_length:
step = -a_length
elif step > a_length:
step = a_length

# Normalize bounded negative values.
if -a_length <= start < 0:
start += a_length
if stop_i and (-a_length <= stop < 0):
stop += a_length

# Handle out-of-bound limits.
if step > 0:
if (start > a_length) or (stop < -a_length):
start = stop = 0
step = 1
else:
if start < -a_length:
start = 0
if stop > a_length:
stop = a_length
elif step < 0:
if (start < -a_length) or (stop_i and stop >= (a_length - 1)):
start = stop = 0
step = 1
else:
if start >= a_length:
start = a_length - 1
if stop_i and stop < -a_length:
stop = None
stop_i = False

# Catch some known empty slices.
if stop_i and (start == stop):
start = stop = 0
step = 1
elif (step > 0) and (stop == 0):
start = stop = 0
step = 1
elif (step < 0) and (stop == -1):
start = stop = 0
step = 1
elif stop_i and (start >= 0) and (stop >= 0):
if (step > 0) and (start > stop):
start = stop = 0
step = 1
elif (step < 0) and (start < stop):
start = stop = 0
step = 1

new_slice = slice(start, stop, step)
if isinstance(a_slice, numbers.Integral):
if new_slice.start == new_slice.stop == 0:
raise IndexError("Index out of range.")
new_slice = new_slice.start

return(new_slice)


def reformat_slices(slices, lengths=None):
"""
Takes a tuple of slices and reformats them to fill in as many undefined
values as possible.
Args:
slices(tuple(slice)): a tuple of slices to reformat.
lengths(tuple(int)): a tuple of lengths to fill.
Returns:
(slice): a tuple of slices with all default
values filled if possible.
Examples:
>>> reformat_slices(
... (
... slice(None),
... slice(3, None),
... slice(None, 5),
... slice(None, None, 2)
... ),
... (10, 13, 15, 20)
... )
(slice(0, 10, 1), slice(3, 13, 1), slice(0, 5, 1), slice(0, 20, 2))
"""

new_slices = slices
if new_slices == tuple():
new_slices = Ellipsis

try:
len(new_slices)
except TypeError:
new_slices = (new_slices,)

new_lengths = lengths
try:
if new_lengths is not None:
len(new_lengths)
except TypeError:
new_lengths = (new_lengths,)

el_idx = None
try:
el_idx = new_slices.index(Ellipsis)
except ValueError:
pass

if new_lengths is not None and el_idx is None:
if len(new_slices) != len(new_lengths):
raise ValueError("Shape must be the same as the number of slices.")
elif new_lengths is not None:
if (len(new_slices) - 1) > len(new_lengths):
raise ValueError(
"Shape must be as large or larger than the number of slices"
" without the Ellipsis."
)

if el_idx is not None:
# Break into three cases.
#
# 1. Before the Ellipsis
# 2. The Ellipsis
# 3. After the Ellipsis
#
# Cases 1 and 3 are trivially solved as before.
# Case 2 is either a no-op or a bunch of `slice(None)`s.
#
# The result is a combination of all of these.

slices_before = new_slices[:el_idx]
slices_after = new_slices[el_idx+1:]

if Ellipsis in slices_before or Ellipsis in slices_after:
raise ValueError("Only one Ellipsis is permitted. Found multiple.")

new_lengths_before = None
new_lengths_after = None
slice_el = (Ellipsis,)
if new_lengths is not None:
pos_before = len(slices_before)
pos_after = len(new_lengths) - len(slices_after)

new_lengths_before = new_lengths[:pos_before]
new_lengths_after = new_lengths[pos_after:]

new_lengths_el = new_lengths[pos_before:pos_after]
slice_el = len(new_lengths_el) * (slice(None),)
if slice_el:
slice_el = reformat_slices(
slice_el,
new_lengths_el
)

if slices_before:
slices_before = reformat_slices(slices_before, new_lengths_before)
if slices_after:
slices_after = reformat_slices(slices_after, new_lengths_after)

new_slices = slices_before + slice_el + slices_after
else:
if new_lengths is None:
new_lengths = [None] * len(new_slices)

new_slices = list(new_slices)
for i, each_length in enumerate(new_lengths):
new_slices[i] = reformat_slice(new_slices[i], each_length)

new_slices = tuple(new_slices)

return(new_slices)
reformat_slice = kenjutsu.format.reformat_slice
reformat_slices = kenjutsu.format.reformat_slices


class UnknownSliceLengthException(Exception):
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