![]() ![]() key: a function whose return value is used as the grouping standard.Returns an iterator that generates a set of values grouped by key This function is just opposite to ifilter If predicate is None, all items in iterable whose False is calculated will be returned. Itertools.ifilterfalse(predicate, iterable)Ĭreate an iterator to generate only items in iterable whose predicate(item) is False. If predicate is None, all the items in iterable calculated to be True will be returned List(takewhile(lambda x: x < 5, ))Ĭreate an iterator to generate only the items whose predicate(item) is True in iterable. If predict returns False, stop the iteration immediately from itertools import takewhile #Starting from 6, the condition of x < 5 is not met, so all items after 6 and 6 need to be returnedĬreate an iterator. If predicate returns False, the items in the iterable and all subsequent items will be generated, that is, the first item that does not meet the condition and all subsequent items will be returned As long as the function predicate(item) is True, discard the items in the iterable. # 2 is also true, and the corresponding value of'd 'is null and falseĬreate an iterator. #selectors: When it is true, the data corresponding to the data bit is reserved when it is false or empty, it is removed from itertools import compressįor x in compress(,): When an element of selectors is true, the element at the corresponding position of data will be retained, otherwise, it will be removed Receive an iterable object as a parameter and return an iterator from itertools import chainĪ = ,] Parameters are multiple iterative objects, as if they are connected by chains import itertoolsįor x in itertools.chain(,): Take multiple iterators as parameters, but only return a single iterator, which generates the contents of all parameter iterators as if they were from a single sequence Object: a duplicate object is required.If times is not provided, the object will be returned endlessly Times (if provided) specifies the repetition count. iterable: an iterative object, which can be a list, string, tuple, etcĬreate an iterator and repeatedly generate the object.This copy is used to return the duplicates in the loop A copy of the elements in iterable will be generated internally. ![]() If it exceeds sys.maxint, the counter will overflow and continue to calculate from - sys.maxint-1Ĭreate an iterator to repeat the loop operation on the elements in iterable. if n is ignored, the calculation starts from 0 (Note: This iterator does not support long integers). Combination iterator: arrangement and combination of sequences, Cartesian product of sequences, etcĬreate an iterator to generate consecutive integers starting from N.Finite iterator: receives one or more sequence s as parameters for combination, grouping and filtering.Infinite iterator: Generate an infinite sequence, such as natural number sequence 1, 2, 3, 4.Itertools can be divided into three categories according to the functions of iterators: Today, let's talk about the common methods in itertools Of course, you can also directly use the next() method to get values. The return value of these functions is an iterator, which is often used in the for loop. Itertools is a built-in module in python that generates various iterators or classes efficiently. ![]()
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