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Update itertools recipes.

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This commit is contained in:
Raymond Hettinger 2010-03-28 18:02:41 +00:00
parent a7e08fe3f8
commit 5b027f87b5
1 changed files with 28 additions and 7 deletions
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35
Doc/library/itertools.rst
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@ -666,9 +666,6 @@ which incur interpreter overhead.
"Return first n items of the iterable as a list"
return list(islice(iterable, n))
def enumerate(iterable, start=0):
return izip(count(start), iterable)
def tabulate(function, start=0):
"Return function(0), function(1), ..."
return imap(function, count(start))
@ -747,10 +744,9 @@ which incur interpreter overhead.
seen = set()
seen_add = seen.add
if key is None:
for element in iterable:
if element not in seen:
seen_add(element)
yield element
for element in ifilterfalse(seen.__contains__, iterable):
seen_add(element)
yield element
else:
for element in iterable:
k = key(element)
@ -763,3 +759,28 @@ which incur interpreter overhead.
# unique_justseen('AAAABBBCCDAABBB') --> A B C D A B
# unique_justseen('ABBCcAD', str.lower) --> A B C A D
return imap(next, imap(itemgetter(1), groupby(iterable, key)))
def iter_except(func, exception, first=None):
""" Call a function repeatedly until an exception is raised.
Converts a call-until-exception interface to an iterator interface.
Like __builtin__.iter(func, sentinel) but uses an exception instead
of a sentinel to end the loop.
Examples:
bsddbiter = iter_except(db.next, bsddb.error, db.first)
heapiter = iter_except(functools.partial(heappop, h), IndexError)
dictiter = iter_except(d.popitem, KeyError)
dequeiter = iter_except(d.popleft, IndexError)
queueiter = iter_except(q.get_nowait, Queue.Empty)
setiter = iter_except(s.pop, KeyError)
"""
try:
if first is not None:
yield first()
while 1:
yield func()
except exception:
pass