python heapq/priority queue/Min heap

Python heapq provides implementation of the heap(min) queue algorithm, also known as the priority queue algorithm. Here's some example code.

from heapq import heappush, heappop

# priority queue normal
h = []
heappush(h, 5)
heappush(h, 1)
heappush(h, 3)

print heappop(h),"size",len(h)
print heappop(h),"size",len(h)
print heappop(h),"size",len(h)

# priority queue with tuple number and string
h = []
heappush(h, (5, "sample text"))
heappush(h, (1, "important text"))
heappush(h, (1, "a important text"))
heappush(h, (9, "un-important text"))

print heappop(h)
print heappop(h)

# priority queue with tuple number only 
h = []
heappush(h, (5, 3))
heappush(h, (7, 3))
heappush(h, (1, 3))
heappush(h, (1, 1))
heappush(h, (1, 2))
heappush(h, (3, 2))
heappush(h, (3, 1))

print heappop(h)
print heappop(h)
print heappop(h)

Output:

1 size 2
3 size 1
5 size 0
(1, 'a important text')
(1, 'important text')
(1, 1)
(1, 2)
(1, 3)

python dequeue data structure

Double-ended queue(dequeue) in python.
All source code available on github

#DA_Dequeue.py

from collections import deque

myDequeue = deque()

myDequeue.append(5) # insert element at back
myDequeue.appendleft(9) # insert element at front
myDequeue.append(55)
myDequeue.appendleft(99)
print myDequeue

print myDequeue.pop() # remove last element
print myDequeue
print myDequeue.popleft() # remove first element
print myDequeue
print myDequeue[-1] # last element
print myDequeue[0] # fist element

Output:

deque([99, 9, 5, 55])
55
deque([99, 9, 5])
99
deque([9, 5])
5
9

python stack data structure

Stack is very important data structure. Here a simple stack implementation.
All source code available on github

 #DA_Stack.py

class MyStack():
    stack = []
    max_stack_size = 2

    def push(self, value):
        if len(self.stack) == self.max_stack_size:
            return "Overflow"
        self.stack.append(value)
    def pop(self):
        if(len(self.stack)):
            return self.stack.pop()
        return "Underflow"

myStack = MyStack()
myStack.push(2)
myStack.push(5)
print myStack.stack
print myStack.push(6)
print myStack.stack
print myStack.pop()
print myStack.stack
print myStack.pop()
print myStack.pop()
print myStack.stack

Output:

[2, 5]
Overflow
[2, 5]
5
[2]
2
Underflow
[]

python queue data structure

Queue implementation using collections.deque.
All source code available on github

#DA_Queue.py

from collections import deque
class MyQueue:
    queue = deque()

    def enqueue(self, value):
        self.queue.append(value)
    def dequeue(self):
        if len(self.queue):
            return self.queue.popleft()
        print "Impossible"


myQueue = MyQueue()
myQueue.enqueue(8)
myQueue.enqueue(4)
print myQueue.queue
myQueue.dequeue()
myQueue.dequeue()
print myQueue.queue
myQueue.dequeue()
print myQueue.queue

Output:

deque([8, 4])
deque([])
Impossible
deque([])