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‎source_py3/python_toolbox/sequence_tools/misc.py‎

Lines changed: 87 additions & 72 deletions
Original file line numberDiff line numberDiff line change
@@ -53,78 +53,93 @@ class NO_FILL_VALUE(misc_tools.NonInstantiable):
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'''
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def partitions(sequence, partition_size=None, n_partitions=None,
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allow_remainder=True, fill_value=NO_FILL_VALUE):
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'''
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Partition `sequence` into equal partitions of size `partition_size`, or
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determine size automatically given the number of partitions as
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`n_partitions`.
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If the sequence can't be divided into precisely equal partitions, the last
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partition will contain less members than all the other partitions.
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Example:
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>>> partitions([0, 1, 2, 3, 4], 2)
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[[0, 1], [2, 3], [4]]
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(You need to give *either* a `partition_size` *or* an `n_partitions`
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argument, not both.)
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Specify `allow_remainder=False` to enforce that the all the partition sizes
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be equal; if there's a remainder while `allow_remainder=False`, an
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exception will be raised.
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If you want the remainder partition to be of equal size with the other
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partitions, you can specify `fill_value` as the padding for the last
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partition. A specified value for `fill_value` implies
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`allow_remainder=True` and will cause an exception to be raised if
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specified with `allow_remainder=False`.
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Example:
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>>> partitions([0, 1, 2, 3, 4], 3, fill_value=None)
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[[0, 1, 2], [3, 4, None]]
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'''
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sequence_length = len(sequence)
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### Validating input: #####################################################
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# #
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if (partition_size is None) == (n_partitions is None):
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raise Exception('You must specify *either* `partition_size` *or* '
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'`n_paritions`.')
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if fill_value is not NO_FILL_VALUE and not allow_remainder:
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raise ValueError('`fill_value` cannot be specified if '
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'`allow_remainder` is `False`.')
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remainder_length = sequence_length % (partition_size if partition_size
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is not None else n_partitions)
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if not allow_remainder and remainder_length > 0:
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raise Exception("You set `allow_remainder=False`, but there's a "
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"reminder of %s left." % remainder_length)
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# #
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### Finished validating input. ############################################
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if partition_size is None:
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partition_size = math_tools.ceil_div(sequence_length, n_partitions)
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if n_partitions is None:
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n_partitions = math_tools.ceil_div(sequence_length, partition_size)
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enlarged_length = partition_size * n_partitions
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blocks = [sequence[i : i + partition_size] for i in
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range(0, enlarged_length, partition_size)]
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if fill_value is not NO_FILL_VALUE and blocks:
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filler = itertools.repeat(fill_value,
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enlarged_length - sequence_length)
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blocks[-1].extend(filler)
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return blocks
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def partitions(sequence, partition_size=None, n_partitions=None,
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allow_remainder=True, larger_on_remainder=False,
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fill_value=NO_FILL_VALUE):
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'''
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Partition `sequence` into equal partitions of size `partition_size`, or
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determine size automatically given the number of partitions as
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`n_partitions`.
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If the sequence can't be divided into precisely equal partitions, the last
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partition will contain less members than all the other partitions.
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Example:
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>>> partitions([0, 1, 2, 3, 4], 2)
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[[0, 1], [2, 3], [4]]
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(You need to give *either* a `partition_size` *or* an `n_partitions`
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argument, not both.)
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Specify `allow_remainder=False` to enforce that the all the partition sizes
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be equal; if there's a remainder while `allow_remainder=False`, an
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exception will be raised.
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By default, if there's a remainder, the last partition will be smaller than
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the others. (e.g. a sequence of 7 items, when partitioned into pairs, will
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have 3 pairs and then a partition with only 1 element.) Specify
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`larger_on_remainder=True` to make the last partition, in case there is
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one, be a bigger partition. (e.g. a sequence of a 7 items divided into
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pairs would result in 2 pairs and one triplet.)
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If you want the remainder partition to be of equal size with the other
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partitions, you can specify `fill_value` as the padding for the last
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partition. A specified value for `fill_value` implies
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`allow_remainder=True` and will cause an exception to be raised if
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specified with `allow_remainder=False`.
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Example:
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>>> partitions([0, 1, 2, 3, 4], 3, fill_value='meow')
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[[0, 1, 2], [3, 4, 'meow']]
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'''
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sequence_length = len(sequence)
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### Validating input: #####################################################
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# #
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if (partition_size is None) + (n_partitions is None) != 1:
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raise Exception('You must specify *either* `partition_size` *or* '
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'`n_paritions`.')
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remainder_length = sequence_length % (partition_size if partition_size
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is not None else n_partitions)
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if not allow_remainder and remainder_length > 0:
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raise Exception("You set `allow_remainder=False`, but there's a "
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"reminder of %s left." % remainder_length)
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# #
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### Finished validating input. ############################################
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if partition_size is None:
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if larger_on_remainder:
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partition_size = sequence_length // n_partitions # (Floor div)
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else:
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partition_size = math_tools.ceil_div(sequence_length, n_partitions)
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if n_partitions is None:
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n_partitions = math_tools.ceil_div(sequence_length, partition_size)
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enlarged_length = partition_size * n_partitions
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blocks = [sequence[i : i + partition_size] for i in
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range(0, enlarged_length, partition_size)]
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if enlarged_length > sequence_length: # We have a remainder
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assert blocks
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if larger_on_remainder:
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if len(blocks) >= 2:
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small_block_to_append_back = blocks[-1]
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del blocks[-1]
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blocks[-1] += small_block_to_append_back
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elif fill_value != NO_FILL_VALUE: # (We use elif because fill is never
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# done if `larger_on_remainder=True`.)
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filler = itertools.repeat(fill_value,
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enlarged_length - sequence_length)
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blocks[-1].extend(filler)
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return blocks
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def is_immutable_sequence(thing):

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