Python Max Heap Data Structure Implementation

Python Max Heap Data Structure Implementation. The following code shows how to implement a max heap in the Python programming language. 

Code:

class MaxHeap:
    def __init__(self, items=[]):
        self.heap = [0]
        for item in items:
            self.push(item)

    def push(self, item):
        self.heap.append(item)
        self.__float_up(self.size() - 1)

    def peak(self):
        if self.heap[1]:
            return self.heap[1]
        else:
            return False

    def pop(self):
        if self.size() < 2:
            return False
        if self.size() == 2:
            return self.heap.pop()

        self.__swap(1, self.size() - 1)
        item = self.heap.pop()
        self.__max_heapify(1)

        return item

    def __swap(self, index1, index2):
        self.heap[index1], self.heap[index2] = self.heap[index2], self.heap[index1]

    def __float_up(self, index):
        parent = index // 2
        if parent < 1:
            return
        elif self.heap[index] > self.heap[parent]:
            self.__swap(index, parent)
            self.__float_up(parent)

    def __max_heapify(self, index):
        largest_idx = index
        left = index * 2
        right = left + 1
        if self.size() > left and self.heap[left] > self.heap[largest_idx]:
            largest_idx = left
        if self.size() > right and self.heap[right] > self.heap[largest_idx]:
            largest_idx = right
        if largest_idx != index:
            self.__swap(index, largest_idx)
            self.__max_heapify(largest_idx)

    def size(self):
        return len(self.heap)


if __name__ == '__main__':
    items = [12, 7, 1, 3, 10, 17, 19, 2, 5]
    heap = MaxHeap(items)
    print(heap.heap[1:])
    print(heap.peak())
    while heap.size() > 1:
        print(heap.pop())

 

Output:

[19, 10, 17, 5, 7, 1, 12, 2, 3]
19
19
17
12
10
7
5
3
2
1