mirror of https://github.com/python/cpython
80 lines
2.0 KiB
Python
80 lines
2.0 KiB
Python
import itertools
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from collections import deque
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from itertools import islice
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# from jaraco.itertools 6.3.0
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class Counter:
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"""
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Wrap an iterable in an object that stores the count of items
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that pass through it.
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>>> items = Counter(range(20))
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>>> items.count
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0
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>>> values = list(items)
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>>> items.count
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20
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"""
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def __init__(self, i):
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self.count = 0
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self.iter = zip(itertools.count(1), i)
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def __iter__(self):
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return self
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def __next__(self):
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self.count, result = next(self.iter)
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return result
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# from more_itertools v8.13.0
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def always_iterable(obj, base_type=(str, bytes)):
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if obj is None:
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return iter(())
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if (base_type is not None) and isinstance(obj, base_type):
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return iter((obj,))
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try:
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return iter(obj)
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except TypeError:
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return iter((obj,))
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# from more_itertools v9.0.0
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def consume(iterator, n=None):
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"""Advance *iterable* by *n* steps. If *n* is ``None``, consume it
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entirely.
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Efficiently exhausts an iterator without returning values. Defaults to
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consuming the whole iterator, but an optional second argument may be
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provided to limit consumption.
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>>> i = (x for x in range(10))
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>>> next(i)
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0
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>>> consume(i, 3)
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>>> next(i)
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4
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>>> consume(i)
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>>> next(i)
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Traceback (most recent call last):
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File "<stdin>", line 1, in <module>
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StopIteration
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If the iterator has fewer items remaining than the provided limit, the
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whole iterator will be consumed.
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>>> i = (x for x in range(3))
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>>> consume(i, 5)
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>>> next(i)
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Traceback (most recent call last):
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File "<stdin>", line 1, in <module>
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StopIteration
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"""
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# Use functions that consume iterators at C speed.
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if n is None:
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# feed the entire iterator into a zero-length deque
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deque(iterator, maxlen=0)
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else:
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# advance to the empty slice starting at position n
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next(islice(iterator, n, n), None)
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