Heap data structure is mainly used to represent a priority queue. In Python, it is available using the “heapq” module. The property of this data structure in Python is that each time the smallest heap element is popped(min-heap).

heapq.ipynb

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     "text": [
      "<class 'list'> [1, 3, 9, 7, 5]\n"
     ]
    }
   ],
   "source": [
    "import heapq\n",
    "\n",
    "li = [5,7,9,1,3]\n",
    "li_copy = li.copy()\n",
    "\n",
    "heapq.heapify(li)\n",
    "heapq.heapify(li_copy)\n",
    "\n",
    "print(type(li), li)"
   ]
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   "outputs": [
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     "name": "stdout",
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     "text": [
      "[1, 3, 4, 7, 5, 9]\n",
      "1\n",
      "3\n",
      "4\n",
      "5\n",
      "7\n",
      "9\n",
      "[]\n",
      "[1, 3, 9, 7, 5]\n"
     ]
    }
   ],
   "source": [
    "heapq.heappush(li_copy, 4)\n",
    "\n",
    "print(li_copy)\n",
    "for _ in range(len(li_copy)):\n",
    "    print(heapq.heappop(li_copy))\n",
    "\n",
    "print(li_copy)\n",
    "print(li)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 21,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[1, 3, 4, 7, 5, 9]\n",
      "1\n",
      "3\n",
      "4\n",
      "5\n",
      "7\n",
      "9\n",
      "[]\n"
     ]
    }
   ],
   "source": [
    "heapq.heappush(li, 4)\n",
    "\n",
    "print(li)\n",
    "for _ in range(len(li)):\n",
    "    print(heapq.heappop(li))\n",
    "print(li)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 25,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[1, 3, 9, 7, 5]\n",
      "1\n",
      "[2, 3, 9, 7, 5]\n"
     ]
    }
   ],
   "source": [
    "# push and pop simultaneously\n",
    "\n",
    "li = [5,7,9,1,3]\n",
    "\n",
    "heapq.heapify(li)\n",
    "print(li)\n",
    "\n",
    "print(heapq.heappushpop(li, 2))\n",
    "print(li)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 26,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[1, 3, 9, 7, 5]\n",
      "1\n",
      "[2, 3, 9, 7, 5]\n"
     ]
    }
   ],
   "source": [
    "# push and pop simultaneously\n",
    "\n",
    "li = [5,7,9,1,3]\n",
    "\n",
    "heapq.heapify(li)\n",
    "print(li)\n",
    "\n",
    "print(heapq.heapreplace(li, 2))\n",
    "print(li)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 28,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[9, 7, 5]\n",
      "[1, 3, 5]\n"
     ]
    }
   ],
   "source": [
    "# find largest and smallest\n",
    "li = [5,7,9,1,3]\n",
    "heapq.heapify(li)\n",
    "\n",
    "print(heapq.nlargest(3, li))\n",
    "print(heapq.nsmallest(3, li))"
   ]
  }
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