If present, the argument must be a function that, when called with any two list items as arguments, returns -1, 0, or 1, depending on whether the first item is to be considered less than, equal to, or greater than the second item for sorting purposes. In Python 2.3, a list’s sort method takes one optional argument. In practice, sort is extremely fast, often preternaturally fast, as it can exploit any order or reverse order that may be present in any sublist (the advanced algorithm sort uses, known as timsort to honor its developer, Tim Peters, is technically a “non-recursive adaptive stable natural mergesort/binary insertion sort hybrid”). For more details, see Sorting a list.Īll mutating methods of list objects, except pop, return None.Ī list’s method sort causes the list to be sorted in-place (its items are reordered to place them in increasing order) in a way that is guaranteed to be stable (elements that compare equal are not exchanged). When argument key is not None, what gets compared for each item x is key ( x ), not x itself. Sorts, in-place, the items of L, comparing items pairwise via the function passed as cmp (by default, the built-in function cmp). sort(cmp=cmp, key=None, reverse=False)(2.4) Sorts, in place, the items of L, comparing items pairwise via function f if f is omitted, comparison is via the built-in function cmp. Returns the value of the item at index i and removes it from L if i is omitted, removes and returns the last item raises an exception if L is empty or i is an invalid index in L. Removes from L the first occurrence of an item in L that is equal to x, or raises an exception if L has no such item. Inserts item x in L before the item at index i, moving following items of L (if any) “rightward” to make space (increases len( L ) by one, does not replace any item, does not raise exceptions: acts just like L =). Returns the index of the first occurrence of an item in L that is equal to x, or raises an exception if L has no such item.Īppends item x to the end of L e.g., L =.Īppends all the items of iterable s to the end of L e.g., L = s. Returns the number of items of L that are equal to x. S is equivalent to S, S is the subsequence of S that includes all items that have an even index in S, and S has the same items as S, but in reverse order. k is the stride of the slice, or the distance between successive indices. Slicing can also use the extended syntax S. An index greater than or equal to L means the end of S, while a negative index less than or equal to - L means the start of S. A negative index indicates the same spot in S as L + n, just like in indexing. Either or both indices may be less than 0. You can even omit both indices, to mean a copy of the entire sequence: S. You can omit j if it is greater than or equal to L, so that the slice extends all the way to the end of S. You can omit i if it is equal to 0, so that the slice begins from the start of S. A slice is an empty subsequence if j is less than or equal to i, or if i is greater than or equal to L, the length of S. In Python, ranges always include the lower bound and exclude the upper bound. S is the subsequence of S from the ith item, included, to the jth item, excluded. To indicate a subsequence of S, you can use a slicing, with the syntax S, where i and j are integers.
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