Index Based Insertion Sort.ipynb

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   "source": [
    "# Index Based Insertion Sort"
   ]
  },
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   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "If the datasets in the list are large, sorting can be achieved on an index alone."
   ]
  },
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   "source": [
    "def insertionsort(a_list):\n",
    "    N = len(a_list)\n",
    "    index = list(range(N))\n",
    "    for i in range(1,N):\n",
    "        elem_idx = index[i]\n",
    "        j = i\n",
    "        while a_list[index[j-1]] > a_list[elem_idx]:\n",
    "            index[j] = index[j-1]\n",
    "            j -= 1\n",
    "        index[j] = elem_idx\n",
    "    return a_list, index"
   ]
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   "outputs": [
    {
     "data": {
      "text/plain": [
       "(['A', 'S', 'O', 'R', 'T', 'I', 'N', 'G', 'E', 'X', 'A', 'M', 'P', 'L', 'E'],\n",
       " [0, 10, 8, 14, 7, 5, 13, 11, 6, 2, 12, 3, 1, 4, 9])"
      ]
     },
     "execution_count": 2,
     "metadata": {},
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   ],
   "source": [
    "insertionsort(list(\"ASORTINGEXAMPLE\"))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "The sorted data is available indirect through the index:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "['A', 'A', 'E', 'E', 'G', 'I', 'L', 'M', 'N', 'O', 'P', 'R', 'S', 'T', 'X']"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "a_list, index = insertionsort(list(\"ASORTINGEXAMPLE\"))\n",
    "sorted_list = [a_list[i] for i in index]\n",
    "sorted_list"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": []
  }
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