But at this point there might be no items left in the queue. The problem is in the pop method: it calls _clear_heap after popping the item (as well as before). You can't pop an item from the queue if it's the only item: > q = PriorityQueueUpdateable()įile "cr163560.py", line 25, in _clear_heap I would appreciate any feedback on improving my code. The code passes this simple test pq = PriorityQueueUpdateable() While (key not in self._dict) or (self._dict != value): Updateable Priority Queue implemented with heapq module and standard python dictionary from heapq import heappush, heappop, heapify Note: Any obsolete values related to an updated key are kept until they are on the top of the queue, at which time they are ignored. I plan to use it in graph search algorithms so the values associated with each key are update-able. nsmallest(k, iterable, key = fun) :- This function is used to return the k smallest elements from the iterable specified and satisfying the key if mentioned.Here is my attempt to implement a minimum priority queue class in Python using the heapq module.nlargest(k, iterable, key = fun) :- This function is used to return the k largest elements from the iterable specified and satisfying the key if mentioned.The popped item using heapreplace() is : 3 The popped item using heappushpop() is : 2 Print ("The popped item using heapreplace() is : ",end="") # using heapreplace() to push and pop items simultaneously Print ("The popped item using heappushpop() is : ",end="") # using heappushpop() to push and pop items simultaneously # using heapify() to convert list into heap heapreplace() returns the smallest value originally in heap regardless of the pushed element as opposed to heappushpop(). In this, element is first popped, then the element is pushed.i.e, the value larger than the pushed value can be returned. heapreplace(heap, ele) :- This function also inserts and pops element in one statement, but it is different from above function.Heap order is maintained after this operation. heappushpop(heap, ele) :- This function combines the functioning of both push and pop operations in one statement, increasing efficiency.Print ("The popped and smallest element is : ",end="") # using heappop() to pop smallest element Print ("The modified heap after push is : ",end="") # using heappush() to push elements into heap # using heapify to convert list into heap # importing "heapq" to implement heap queue The order is adjusted, so as heap structure is maintained. heappop(heap) :- This function is used to remove and return the smallest element from heap.heappush(heap, ele) :- This function is used to insert the element mentioned in its arguments into heap. heapify(iterable) :- This function is used to convert the iterable into a heap data structure.The heap element also returns the smallest element each time. Whenever elements are pushed or popped, heap structure in maintained. The property of this data structure in Python is that each time the smallest of heap element is popped(min heap). In Python, it is available using “heapq” module. Heap data structure is mainly used to represent a priority queue. Function Decorators in Python | Set 1 (Introduction).When to use yield instead of return in Python?.How to write an empty function in Python – pass statement?.class method vs static method in Python.Python | Difference between iterable and iterator.Python _iter_() and _next_() | Converting an object into an iterator.Using else conditional statement with for loop in python.Chaining comparison operators in Python.Programs for printing pyramid patterns in Python.Loops and Control Statements (continue, break and pass) in Python.Python Membership and Identity Operators.Difference between = and is operator in Python.Inplace vs Standard Operators in Python.G-Fact 19 (Logical and Bitwise Not Operators on Boolean).Print Single and Multiple variable in Python.Packing and Unpacking Arguments in Python.What is the maximum possible value of an integer in Python ?.Set 2 (Variables, Expressions, Conditions and Functions).Python | Set 3 (Strings, Lists, Tuples, Iterations).Vulnerability in input() function – Python 2.x.Python Input Methods for Competitive Programming.Taking multiple inputs from user in Python.Python Language advantages and applications.How to print without newline in Python?.How to assign values to variables in Python and other languages.How to check if a string is a valid keyword in Python?.Statement, Indentation and Comment in Python.Important differences between Python 2.x and Python 3.x with examples.
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