![]() ![]() ![]() position = pos # Restore invariant by sifting up self. pop () return # Replace elt with last element last = self. position except KeyError : # Not in queue raise # If elt is last item, remove and return if pos = len ( self. def remove ( self, elt ): """Remove an element from the queue.""" # Find and remove element try : pos = self. Introduction to algorithms second edition. element def _repr_ ( self ): return f "_HeapElement( ) References. _hash def _getitem_ ( self, indx ): return self. element = other def _hash_ ( self ): return self. element except AttributeError : return self. priority > other_priority def _eq_ ( self, other ): try : return self. ![]() element except TypeError as err : raise TypeError ( "Consider using a tuple, with a priority value that can be compared." ) return self. priority = other_priority : try : return self. priority other # assume comparing to another _HeapElement if self. priority except AttributeError : return self. _hash = hash ( element ) def _lt_ ( self, other ): try : other_priority = other. """ _slots_ = def _init_ ( self, priority, element ): self. This provides compatibility with older systems that use tuples to combine priority and elements. In `greedy_modularity_communities()` the following code is used to check that two _HeapElements differ in either element or priority: if d_oldmax != row_max or d_oldmax.priority != row_max.priority: If the priorities are the same, this implementation uses the element as a tiebreaker. Unfortunately, this class can be tricky to work with if you forget that `_lt_` compares the priority while `_eq_` compares the element. So, we need inequalities to look at the priority (for sorting) and equality (and hash) to look at the element to enable updates to the priority. The idea is that using a 2-tuple (priority, element) works for sorting, but not for dict lookup because priorities are often floating point values so round-off can mess up equality. """ import heapq _all_ = class _HeapElement : """This proxy class separates the heap element from its priority. """Priority queue class with updatable priorities. ![]()
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