Day 9 in Sense

[ou-summer-of-code-2017.git] / 01-ticket-prices / ticket-pricing-solution.ipynb

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   "cell_type": "markdown",
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   "source": [
    "# Ticket pricing\n",
    "\n",
    "You've been shopping around for a holiday package deal and its time to make your choice of which deal to go with. The file [01-holidays.txt](01-holidays.txt) contains a summary of your investigations. \n",
    "\n",
    "It's a simple text file, with one possible holiday package per line.\n",
    "\n",
    "Each line has four fields, separated by spaces. They are:\n",
    "* The deal ID, from the price comparison website you found it.\n",
    "* The holiday price, in whole pounds.\n",
    "* The location of the holiday, always a single word.\n",
    "* The number of nights you'd be staying. \n",
    "\n",
    "For example, the data file might look like this:\n",
    "\n",
    "```\n",
    "db61bb90 769 Morgantown 3\n",
    "202c898b5f 1284 Morgantown 21\n",
    "def36ffcd 1514 Giessenmestia 21\n",
    "389018bd0707 1052 Estacada 21\n",
    "a487c4270 782 Geoje-Si 14\n",
    "6caf2584a55 724 Stonington-Island 14\n",
    "199608abc5 1209 Nordkapp 21\n",
    "```"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Part 1\n",
    "You have a budget of £1200. How many of the holidays can you afford?\n",
    "\n",
    "Given the example data above, you could afford four of the holidays: the trips to Estacada, Geoje-Si and Stonnington-Island, and the three-day trip to Morgantown. \n",
    "\n",
    "The 21 day trip to Morgantown and the trips to  Giessenmestia and Nordkapp are all too expensive."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Solution"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[['dda7d369', '1546', 'Uzupis', '21'],\n",
       " ['68022753', '1239', 'Mamula', '21'],\n",
       " ['b261dbd1cef', '996', 'Holmegaard', '21']]"
      ]
     },
     "execution_count": 12,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "holidays = []\n",
    "with open('01-holidays.txt') as f:\n",
    "    for hol_line in f.readlines():\n",
    "        holidays.append(hol_line.split())\n",
    "        \n",
    "holidays[:3]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "59"
      ]
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     "execution_count": 13,
     "metadata": {},
     "output_type": "execute_result"
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   ],
   "source": [
    "affordable_holidays = []\n",
    "for h in holidays:\n",
    "    if int(h[1]) <= 1200:\n",
    "        affordable_holidays.append(h)\n",
    "\n",
    "len(affordable_holidays)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
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    {
     "data": {
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       "124"
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     "execution_count": 14,
     "metadata": {},
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   ],
   "source": [
    "len(holidays)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Smart-alec one-line solution"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "59"
      ]
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     "execution_count": 15,
     "metadata": {},
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   ],
   "source": [
    "sum(1 for h in open('01-holidays.txt').readlines() if int(h.split()[1]) <= 1200)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Part 2\n",
    "You don't just want _a_ holiday. You want the _best_ holiday. What is the code of the holiday which would give you the best value?\n",
    "\n",
    "The \"value\" of a holiday is the duration per pound. Because some destinations are better than others, you'll want to scale the value for some locations. For instance, a night in Timbuktu is worth three times as much as a holiday in Bletchley.\n",
    "\n",
    "Assume all holidays have a relative value of 1, apart from these destinations.\n",
    "\n",
    "| Destination | Score |\n",
    "|-------------|-------|\n",
    "| Almaty | 2.0 |\n",
    "| Brorfelde | 0.9 |\n",
    "| Estacada | 0.4 |\n",
    "| Jayuya | 0.6 |\n",
    "| Karlukovo | 2.2 |\n",
    "| Morgantown | 2.9 |\n",
    "| Nordkapp | 1.5 |\n",
    "| Nullarbor | 2.2 |\n",
    "| Puente-Laguna-Garzonkuala-Penyu | 0.4 |\n",
    "| Uzupis | 0.9 |\n",
    "\n",
    "## Example\n",
    "\n",
    "Given the holiday list above, the holiday to Geoje-Si (with the standard weighting of 1) has a value of $\\frac{14}{782} = 0.0179$ nights per pound. \n",
    "\n",
    "The trip to Estacada looks promising, at $\\frac{21}{1052} = 0.0200$ nights per pound. Unfortunately, the weighting for Estacada is low, to the adjusted cost is $0.4 \\times \\frac{21}{1052} = 0.00798$ nights per pound.\n",
    "\n",
    "The best value holiday is the 21 day trip to Morgantown, with a value of $2.9 \\times \\frac{21}{1284} = 0.0474$ nights per pound. Unfortunately, it's unaffordable. \n",
    "\n",
    "The best value affordable holiday is the trip to Stonnington Island, with $\\frac{14}{1284} = 0.0193$ nights per pound."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "metadata": {
    "collapsed": true
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   "outputs": [],
   "source": [
    "destination_values = {'Almaty': 2.0, 'Brorfelde': 0.9, 'Estacada': 0.4, 'Jayuya': 0.6, 'Karlukovo': 2.2, \n",
    "                      'Morgantown': 2.9,'Nordkapp': 1.5, 'Nullarbor': 2.2, \n",
    "                      'Puente-Laguna-Garzonkuala-Penyu': 0.4, 'Uzupis': 0.9}"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 17,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "def value_of_destination(name):\n",
    "    if name in destination_values:\n",
    "        return destination_values[name]\n",
    "    else:\n",
    "        return 1"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "def value_of_holiday(holiday):\n",
    "    hid, cost, destination, duration = tuple(holiday)\n",
    "    value = value_of_destination(destination) * float(duration) / int(cost)\n",
    "    return value"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 19,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'ee064e1e2ea'"
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     "execution_count": 19,
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   "source": [
    "best_holiday = ''\n",
    "best_value = 0\n",
    "\n",
    "for h in affordable_holidays:\n",
    "    if value_of_holiday(h) > best_value:\n",
    "        best_value = value_of_holiday(h)\n",
    "        best_holiday = h[0]\n",
    "        \n",
    "best_holiday"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Smart-alec solution"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 20,
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    {
     "data": {
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       "'ee064e1e2ea'"
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     "execution_count": 20,
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   ],
   "source": [
    "# Right answer\n",
    "max(affordable_holidays, key=value_of_holiday)[0]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 21,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'c86e2e5826'"
      ]
     },
     "execution_count": 21,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Answer if you don't filter by affordability\n",
    "max(holidays, key=value_of_holiday)[0]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 23,
   "metadata": {},
   "outputs": [
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       "'f60e203aaaf9'"
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     "execution_count": 23,
     "metadata": {},
     "output_type": "execute_result"
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   ],
   "source": [
    "# Answer if you don't scale by perceived value\n",
    "max(affordable_holidays, key=lambda h: float(h[3]) / float(h[1]))[0]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 22,
   "metadata": {},
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     "data": {
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     "execution_count": 22,
     "metadata": {},
     "output_type": "execute_result"
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   ],
   "source": [
    "# Answer if you don't scale by perceived value, AND don't filter by affordability\n",
    "max(holidays, key=lambda h: float(h[3]) / float(h[1]))[0]"
   ]
  }
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