Queues

class pydatastructs.Queue(implementation='array', **kwargs)

Representation of queue data structure.

Parameters

• implementation (str) – Implementation to be used for queue. By default, ‘array’

• items (list/tuple) – Optional, by default, None The inital items in the queue.

• dtype (A valid python type) – Optional, by default NoneType if item is None. Required only for ‘array’ implementation.

• double_ended (bool) – Optional, by default, False. Set to True if the queue should support additional, appendleft and pop operations from left and right sides respectively.

Examples

>>> from pydatastructs import Queue
>>> q = Queue()
>>> q.append(1)
>>> q.append(2)
>>> q.append(3)
>>> q.popleft()
1
>>> len(q)
2

References

1

https://en.wikipedia.org/wiki/Queue_(abstract_data_type)

append(*args, **kwargs)

appendleft(*args, **kwargs)

pop(*args, **kwargs)

popleft(*args, **kwargs)

property is_empty

__module__ = 'pydatastructs.miscellaneous_data_structures.queue'

class pydatastructs.PriorityQueue(implementation='binary_heap', **kwargs)

Represents the concept of priority queue.

Parameters

• implementation (str) –

  The implementation which is to be used for supporting operations of priority queue. The following implementations are supported, ‘linked_list’ -> Linked list implementation. ‘binary_heap’ -> Binary heap implementation. ‘binomial_heap’ -> Binomial heap implementation.

  Doesn’t support custom comparators, minimum key data is extracted in every pop.

  Optional, by default, ‘binary_heap’ implementation is used.

• comp (function) – The comparator to be used while comparing priorities. Must return a bool object. By default, lambda u, v: u < v is used to compare priorities i.e., minimum priority elements are extracted by pop operation.

Examples

>>> from pydatastructs import PriorityQueue
>>> pq = PriorityQueue()
>>> pq.push(1, 2)
>>> pq.push(2, 3)
>>> pq.pop()
1
>>> pq2 = PriorityQueue(comp=lambda u, v: u > v)
>>> pq2.push(1, 2)
>>> pq2.push(2, 3)
>>> pq2.pop()
2

References

1

https://en.wikipedia.org/wiki/Priority_queue

push(value, priority)

Pushes the value to the priority queue according to the given priority.

value

Value to be pushed.

priority

Priority to be given to the value.

pop()

Pops out the value from the priority queue.

property peek

Returns the pointer to the value which will be popped out by pop method.

property is_empty

Checks if the priority queue is empty.

__module__ = 'pydatastructs.miscellaneous_data_structures.queue'