Limnoria/src/utils/iter.py

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###
# Copyright (c) 2002-2005, Jeremiah Fincher
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
# * Redistributions of source code must retain the above copyright notice,
# this list of conditions, and the following disclaimer.
# * Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions, and the following disclaimer in the
# documentation and/or other materials provided with the distribution.
# * Neither the name of the author of this software nor the name of
# contributors to this software may be used to endorse or promote products
# derived from this software without specific prior written consent.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
###
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from __future__ import division
import sys
import new
import random
from itertools import *
def len(iterable):
"""Returns the length of an iterator."""
i = 0
for _ in iterable:
i += 1
return i
def trueCycle(iterable):
while 1:
yielded = False
for x in iterable:
yield x
yielded = True
if not yielded:
raise StopIteration
if sys.version_info < (2, 4, 0):
def groupby(key, iterable):
if key is None:
key = lambda x: x
it = iter(iterable)
value = it.next() # If there are no items, this takes an early exit
oldkey = key(value)
group = [value]
for value in it:
newkey = key(value)
if newkey != oldkey:
yield group
group = []
oldkey = newkey
group.append(value)
yield group
def partition(p, iterable):
"""Partitions an iterable based on a predicate p.
Returns a (yes,no) tuple"""
no = []
yes = []
for elt in iterable:
if p(elt):
yes.append(elt)
else:
no.append(elt)
return (yes, no)
def any(p, iterable):
"""Returns true if any element in iterable satisfies predicate p."""
for elt in ifilter(p, iterable):
return True
else:
return False
def all(p, iterable):
"""Returns true if all elements in iterable satisfy predicate p."""
for elt in ifilterfalse(p, iterable):
return False
else:
return True
def choice(iterable):
if isinstance(iterable, (list, tuple)):
return random.choice(iterable)
else:
n = 1
m = new.module('') # Guaranteed unique value.
ret = m
for x in iterable:
if random.random() < 1/n:
ret = x
n += 1
if ret is m:
raise IndexError
return ret
def flatten(iterable, strings=False):
"""Flattens a list of lists into a single list. See the test for examples.
"""
for elt in iterable:
if not strings and isinstance(elt, basestring):
yield elt
else:
try:
for x in flatten(elt):
yield x
except TypeError:
yield elt
def split(isSeparator, iterable, maxsplit=-1, yieldEmpty=False):
"""split(isSeparator, iterable, maxsplit=-1, yieldEmpty=False)
Splits an iterator based on a predicate isSeparator."""
if isinstance(isSeparator, basestring):
f = lambda s: s == isSeparator
else:
f = isSeparator
acc = []
for element in iterable:
if maxsplit == 0 or not f(element):
acc.append(element)
else:
maxsplit -= 1
if acc or yieldEmpty:
yield acc
acc = []
if acc or yieldEmpty:
yield acc
def ilen(iterable):
i = 0
for _ in iterable:
i += 1
return i
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def startswith(long, short):
longI = iter(long)
shortI = iter(short)
try:
while True:
if shortI.next() != longI.next():
return False
except StopIteration:
return True
def limited(iterable, limit):
i = limit
iterable = iter(iterable)
try:
while i:
yield iterable.next()
i -= 1
except StopIteration:
raise ValueError, 'Expected %s elements in iterable (%r), got %s.' % \
(limit, iterable, limit-i)
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