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Functional tools for creating and using iterators.
Infinite iterators:
count(start=0, step=1) --> start, start+step, start+2*step, ...
cycle(p) --> p0, p1, ... plast, p0, p1, ...
repeat(elem [,n]) --> elem, elem, elem, ... endlessly or up to n times
Iterators terminating on the shortest input sequence:
accumulate(p[, func]) --> p0, p0+p1, p0+p1+p2
chain(p, q, ...) --> p0, p1, ... plast, q0, q1, ...
chain.from_iterable([p, q, ...]) --> p0, p1, ... plast, q0, q1, ...
compress(data, selectors) --> (d[0] if s[0]), (d[1] if s[1]), ...
dropwhile(pred, seq) --> seq[n], seq[n+1], starting when pred fails
groupby(iterable[, keyfunc]) --> sub-iterators grouped by value of keyfunc(v)
filterfalse(pred, seq) --> elements of seq where pred(elem) is False
islice(seq, [start,] stop [, step]) --> elements from
seq[start:stop:step]
pairwise(s) --> (s[0],s[1]), (s[1],s[2]), (s[2], s[3]), ...
starmap(fun, seq) --> fun(*seq[0]), fun(*seq[1]), ...
tee(it, n=2) --> (it1, it2 , ... itn) splits one iterator into n
takewhile(pred, seq) --> seq[0], seq[1], until pred fails
zip_longest(p, q, ...) --> (p[0], q[0]), (p[1], q[1]), ...
Combinatoric generators:
product(p, q, ... [repeat=1]) --> cartesian product
permutations(p[, r])
combinations(p, r)
combinations_with_replacement(p, r)
Return series of accumulated sums (or other binary function results).
chain(*iterables) --> chain object Return a chain object whose .__next__() method returns elements from the first iterable until it is exhausted, then elements from the next iterable, until all of the iterables are exhausted.
from_iterable(iterable, /) Alternative chain() constructor taking a single iterable argument that evaluates lazily.
Return successive r-length combinations of elements in the iterable. combinations(range(4), 3) --> (0,1,2), (0,1,3), (0,2,3), (1,2,3)
Return successive r-length combinations of elements in the iterable allowing individual elements to have successive repeats.
combinations_with_replacement('ABC', 2) --> ('A','A'), ('A','B'), ('A','C'), ('B','B'), ('B','C'), ('C','C')
Return data elements corresponding to true selector elements. Forms a shorter iterator from selected data elements using the selectors to choose the data elements.
Return a count object whose .__next__() method returns consecutive values.
Equivalent to:
def count(firstval=0, step=1):
x = firstval
while 1:
yield x
x += step
Return elements from the iterable until it is exhausted. Then repeat the sequence indefinitely.
Drop items from the iterable while predicate(item) is true. Afterwards, return every element until the iterable is exhausted.
Return those items of iterable for which function(item) is false. If function is None, return the items that are false.
make an iterator that returns consecutive keys and groups from the iterable
iterable
Elements to divide into groups according to the key function.
key
A function for computing the group category for each element.
If the key function is not specified or is None, the element itself
is used for grouping.
islice(iterable, stop) --> islice object islice(iterable, start, stop[, step]) --> islice object Return an iterator whose next() method returns selected values from an iterable. If start is specified, will skip all preceding elements; otherwise, start defaults to zero. Step defaults to one. If specified as another value, step determines how many values are skipped between successive calls. Works like a slice() on a list but returns an iterator.
Return an iterator of overlapping pairs taken from the input iterator.
s -> (s0,s1), (s1,s2), (s2, s3), ...
Return successive r-length permutations of elements in the iterable. permutations(range(3), 2) --> (0,1), (0,2), (1,0), (1,2), (2,0), (2,1)
product(*iterables, repeat=1) --> product object
Cartesian product of input iterables. Equivalent to nested for-loops.
For example, product(A, B) returns the same as: ((x,y) for x in A for y in B).
The leftmost iterators are in the outermost for-loop, so the output tuples
cycle in a manner similar to an odometer (with the rightmost element changing
on every iteration).
To compute the product of an iterable with itself, specify the number
of repetitions with the optional repeat keyword argument. For example,
product(A, repeat=4) means the same as product(A, A, A, A).
product('ab', range(3)) --> ('a',0) ('a',1) ('a',2) ('b',0) ('b',1) ('b',2)
product((0,1), (0,1), (0,1)) --> (0,0,0) (0,0,1) (0,1,0) (0,1,1) (1,0,0) ...
repeat(object [,times]) -> create an iterator which returns the object for the specified number of times. If not specified, returns the object endlessly.
Return an iterator whose values are returned from the function evaluated with an argument tuple taken from the given sequence.
Return successive entries from an iterable as long as the predicate evaluates to true for each entry.
zip_longest(iter1 [,iter2 [...]], [fillvalue=None]) --> zip_longest object Return a zip_longest object whose .__next__() method returns a tuple where the i-th element comes from the i-th iterable argument. The .__next__() method continues until the longest iterable in the argument sequence is exhausted and then it raises StopIteration. When the shorter iterables are exhausted, the fillvalue is substituted in their place. The fillvalue defaults to None or can be specified by a keyword argument.
tee(iterable, n=2, /) Returns a tuple of n independent iterators.