List objects support additional operations that allow in-place modification of the object. These operations would be supported by other mutable sequence types (when added to the language) as well. Strings and tuples are immutable sequence types and such objects cannot be modified once created. The following operations are defined on mutable sequence types (where x is an arbitrary object):
, Notes:
sort()
method takes an optional argument
specifying a comparison function of two arguments (list items) which
should return -1
, 0
or 1
depending on whether the
first argument is considered smaller than, equal to, or larger than the
second argument. Note that this slows the sorting process down
considerably; e.g. to sort a list in reverse order it is much faster
to use calls to sort()
and reverse()
than to use
sort()
with a comparison function that reverses the ordering of
the elements.
sort()
and reverse()
methods modify the
list in place for economy of space when sorting or reversing a large
list. They don't return the sorted or reversed list to remind you of
this side effect.