D7net
Home
Console
Upload
information
Create File
Create Folder
About
Tools
:
/
proc
/
self
/
root
/
opt
/
alt
/
python37
/
lib64
/
python3.7
/
site-packages
/
pyrsistent
/
Filename :
_pbag.py
back
Copy
from ._compat import Container, Iterable, Sized, Hashable from functools import reduce from pyrsistent._pmap import pmap def _add_to_counters(counters, element): return counters.set(element, counters.get(element, 0) + 1) class PBag(object): """ A persistent bag/multiset type. Requires elements to be hashable, and allows duplicates, but has no ordering. Bags are hashable. Do not instantiate directly, instead use the factory functions :py:func:`b` or :py:func:`pbag` to create an instance. Some examples: >>> s = pbag([1, 2, 3, 1]) >>> s2 = s.add(4) >>> s3 = s2.remove(1) >>> s pbag([1, 1, 2, 3]) >>> s2 pbag([1, 1, 2, 3, 4]) >>> s3 pbag([1, 2, 3, 4]) """ __slots__ = ('_counts', '__weakref__') def __init__(self, counts): self._counts = counts def add(self, element): """ Add an element to the bag. >>> s = pbag([1]) >>> s2 = s.add(1) >>> s3 = s.add(2) >>> s2 pbag([1, 1]) >>> s3 pbag([1, 2]) """ return PBag(_add_to_counters(self._counts, element)) def update(self, iterable): """ Update bag with all elements in iterable. >>> s = pbag([1]) >>> s.update([1, 2]) pbag([1, 1, 2]) """ if iterable: return PBag(reduce(_add_to_counters, iterable, self._counts)) return self def remove(self, element): """ Remove an element from the bag. >>> s = pbag([1, 1, 2]) >>> s2 = s.remove(1) >>> s3 = s.remove(2) >>> s2 pbag([1, 2]) >>> s3 pbag([1, 1]) """ if element not in self._counts: raise KeyError(element) elif self._counts[element] == 1: newc = self._counts.remove(element) else: newc = self._counts.set(element, self._counts[element] - 1) return PBag(newc) def count(self, element): """ Return the number of times an element appears. >>> pbag([]).count('non-existent') 0 >>> pbag([1, 1, 2]).count(1) 2 """ return self._counts.get(element, 0) def __len__(self): """ Return the length including duplicates. >>> len(pbag([1, 1, 2])) 3 """ return sum(self._counts.itervalues()) def __iter__(self): """ Return an iterator of all elements, including duplicates. >>> list(pbag([1, 1, 2])) [1, 1, 2] >>> list(pbag([1, 2])) [1, 2] """ for elt, count in self._counts.iteritems(): for i in range(count): yield elt def __contains__(self, elt): """ Check if an element is in the bag. >>> 1 in pbag([1, 1, 2]) True >>> 0 in pbag([1, 2]) False """ return elt in self._counts def __repr__(self): return "pbag({0})".format(list(self)) def __eq__(self, other): """ Check if two bags are equivalent, honoring the number of duplicates, and ignoring insertion order. >>> pbag([1, 1, 2]) == pbag([1, 2]) False >>> pbag([2, 1, 0]) == pbag([0, 1, 2]) True """ if type(other) is not PBag: raise TypeError("Can only compare PBag with PBags") return self._counts == other._counts def __lt__(self, other): raise TypeError('PBags are not orderable') __le__ = __lt__ __gt__ = __lt__ __ge__ = __lt__ # Multiset-style operations similar to collections.Counter def __add__(self, other): """ Combine elements from two PBags. >>> pbag([1, 2, 2]) + pbag([2, 3, 3]) pbag([1, 2, 2, 2, 3, 3]) """ if not isinstance(other, PBag): return NotImplemented result = self._counts.evolver() for elem, other_count in other._counts.iteritems(): result[elem] = self.count(elem) + other_count return PBag(result.persistent()) def __sub__(self, other): """ Remove elements from one PBag that are present in another. >>> pbag([1, 2, 2, 2, 3]) - pbag([2, 3, 3, 4]) pbag([1, 2, 2]) """ if not isinstance(other, PBag): return NotImplemented result = self._counts.evolver() for elem, other_count in other._counts.iteritems(): newcount = self.count(elem) - other_count if newcount > 0: result[elem] = newcount elif elem in self: result.remove(elem) return PBag(result.persistent()) def __or__(self, other): """ Union: Keep elements that are present in either of two PBags. >>> pbag([1, 2, 2, 2]) | pbag([2, 3, 3]) pbag([1, 2, 2, 2, 3, 3]) """ if not isinstance(other, PBag): return NotImplemented result = self._counts.evolver() for elem, other_count in other._counts.iteritems(): count = self.count(elem) newcount = max(count, other_count) result[elem] = newcount return PBag(result.persistent()) def __and__(self, other): """ Intersection: Only keep elements that are present in both PBags. >>> pbag([1, 2, 2, 2]) & pbag([2, 3, 3]) pbag([2]) """ if not isinstance(other, PBag): return NotImplemented result = pmap().evolver() for elem, count in self._counts.iteritems(): newcount = min(count, other.count(elem)) if newcount > 0: result[elem] = newcount return PBag(result.persistent()) def __hash__(self): """ Hash based on value of elements. >>> m = pmap({pbag([1, 2]): "it's here!"}) >>> m[pbag([2, 1])] "it's here!" >>> pbag([1, 1, 2]) in m False """ return hash(self._counts) Container.register(PBag) Iterable.register(PBag) Sized.register(PBag) Hashable.register(PBag) def b(*elements): """ Construct a persistent bag. Takes an arbitrary number of arguments to insert into the new persistent bag. >>> b(1, 2, 3, 2) pbag([1, 2, 2, 3]) """ return pbag(elements) def pbag(elements): """ Convert an iterable to a persistent bag. Takes an iterable with elements to insert. >>> pbag([1, 2, 3, 2]) pbag([1, 2, 2, 3]) """ if not elements: return _EMPTY_PBAG return PBag(reduce(_add_to_counters, elements, pmap())) _EMPTY_PBAG = PBag(pmap())