01-ticket-prices/ticket-pricing-solution.ipynb

   1 {
   2  "cells": [
   3   {
   4    "cell_type": "markdown",
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   6    "source": [
   7     "# Ticket pricing\n",
   8     "\n",
   9     "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",
  10     "\n",
  11     "It's a simple text file, with one possible holiday package per line.\n",
  12     "\n",
  13     "Each line has four fields, separated by spaces. They are:\n",
  14     "* The deal ID, from the price comparison website you found it.\n",
  15     "* The holiday price, in whole pounds.\n",
  16     "* The location of the holiday, always a single word.\n",
  17     "* The number of nights you'd be staying. \n",
  18     "\n",
  19     "For example, the data file might look like this:\n",
  20     "\n",
  21     "```\n",
  22     "db61bb90 769 Morgantown 3\n",
  23     "202c898b5f 1284 Morgantown 21\n",
  24     "def36ffcd 1514 Giessenmestia 21\n",
  25     "389018bd0707 1052 Estacada 21\n",
  26     "a487c4270 782 Geoje-Si 14\n",
  27     "6caf2584a55 724 Stonington-Island 14\n",
  28     "199608abc5 1209 Nordkapp 21\n",
  29     "```"
  30    ]
  31   },
  32   {
  33    "cell_type": "markdown",
  34    "metadata": {},
  35    "source": [
  36     "## Part 1\n",
  37     "You have a budget of £1200. How many of the holidays can you afford?\n",
  38     "\n",
  39     "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",
  40     "\n",
  41     "The 21 day trip to Morgantown and the trips to  Giessenmestia and Nordkapp are all too expensive."
  42    ]
  43   },
  44   {
  45    "cell_type": "markdown",
  46    "metadata": {},
  47    "source": [
  48     "### Solution"
  49    ]
  50   },
  51   {
  52    "cell_type": "code",
  53    "execution_count": 2,
  54    "metadata": {},
  55    "outputs": [
  56     {
  57      "data": {
  58       "text/plain": [
  59        "[['dda7d369', '1546', 'Uzupis', '21'],\n",
  60        " ['68022753', '1239', 'Mamula', '21'],\n",
  61        " ['b261dbd1cef', '996', 'Holmegaard', '21']]"
  62       ]
  63      },
  64      "execution_count": 2,
  65      "metadata": {},
  66      "output_type": "execute_result"
  67     }
  68    ],
  69    "source": [
  70     "holidays = []\n",
  71     "with open('01-holidays.txt') as f:\n",
  72     "    for hol_line in f:\n",
  73     "        holidays.append(hol_line.split())\n",
  74     "        \n",
  75     "holidays[:3]"
  76    ]
  77   },
  78   {
  79    "cell_type": "code",
  80    "execution_count": 3,
  81    "metadata": {},
  82    "outputs": [
  83     {
  84      "data": {
  85       "text/plain": [
  86        "[['dda7d369', '1546', 'Uzupis', '21'],\n",
  87        " ['68022753', '1239', 'Mamula', '21'],\n",
  88        " ['b261dbd1cef', '996', 'Holmegaard', '21']]"
  89       ]
  90      },
  91      "execution_count": 3,
  92      "metadata": {},
  93      "output_type": "execute_result"
  94     }
  95    ],
  96    "source": [
  97     "holidays = [line.split() for line in open('01-holidays.txt')]\n",
  98     "        \n",
  99     "holidays[:3]"
 100    ]
 101   },
 102   {
 103    "cell_type": "code",
 104    "execution_count": 13,
 105    "metadata": {},
 106    "outputs": [
 107     {
 108      "data": {
 109       "text/plain": [
 110        "59"
 111       ]
 112      },
 113      "execution_count": 13,
 114      "metadata": {},
 115      "output_type": "execute_result"
 116     }
 117    ],
 118    "source": [
 119     "affordable_holidays = []\n",
 120     "for h in holidays:\n",
 121     "    if int(h[1]) <= 1200:\n",
 122     "        affordable_holidays.append(h)\n",
 123     "\n",
 124     "len(affordable_holidays)"
 125    ]
 126   },
 127   {
 128    "cell_type": "code",
 129    "execution_count": 5,
 130    "metadata": {},
 131    "outputs": [
 132     {
 133      "data": {
 134       "text/plain": [
 135        "59"
 136       ]
 137      },
 138      "execution_count": 5,
 139      "metadata": {},
 140      "output_type": "execute_result"
 141     }
 142    ],
 143    "source": [
 144     "affordable_holidays = [h for h in holidays if int(h[1]) <= 1200]\n",
 145     "len(affordable_holidays)"
 146    ]
 147   },
 148   {
 149    "cell_type": "code",
 150    "execution_count": 14,
 151    "metadata": {},
 152    "outputs": [
 153     {
 154      "data": {
 155       "text/plain": [
 156        "124"
 157       ]
 158      },
 159      "execution_count": 14,
 160      "metadata": {},
 161      "output_type": "execute_result"
 162     }
 163    ],
 164    "source": [
 165     "len(holidays)"
 166    ]
 167   },
 168   {
 169    "cell_type": "markdown",
 170    "metadata": {},
 171    "source": [
 172     "### Smart-alec one-line solution"
 173    ]
 174   },
 175   {
 176    "cell_type": "code",
 177    "execution_count": 4,
 178    "metadata": {},
 179    "outputs": [
 180     {
 181      "data": {
 182       "text/plain": [
 183        "59"
 184       ]
 185      },
 186      "execution_count": 4,
 187      "metadata": {},
 188      "output_type": "execute_result"
 189     }
 190    ],
 191    "source": [
 192     "sum(1 for h in open('01-holidays.txt') if int(h.split()[1]) <= 1200)"
 193    ]
 194   },
 195   {
 196    "cell_type": "markdown",
 197    "metadata": {},
 198    "source": [
 199     "# Part 2\n",
 200     "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",
 201     "\n",
 202     "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",
 203     "\n",
 204     "Assume all holidays have a relative value of 1, apart from these destinations.\n",
 205     "\n",
 206     "| Destination | Score |\n",
 207     "|-------------|-------|\n",
 208     "| Almaty | 2.0 |\n",
 209     "| Brorfelde | 0.9 |\n",
 210     "| Estacada | 0.4 |\n",
 211     "| Jayuya | 0.6 |\n",
 212     "| Karlukovo | 2.2 |\n",
 213     "| Morgantown | 2.9 |\n",
 214     "| Nordkapp | 1.5 |\n",
 215     "| Nullarbor | 2.2 |\n",
 216     "| Puente-Laguna-Garzonkuala-Penyu | 0.4 |\n",
 217     "| Uzupis | 0.9 |\n",
 218     "\n",
 219     "## Example\n",
 220     "\n",
 221     "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",
 222     "\n",
 223     "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",
 224     "\n",
 225     "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",
 226     "\n",
 227     "The best value affordable holiday is the trip to Stonnington Island, with $\\frac{14}{1284} = 0.0193$ nights per pound."
 228    ]
 229   },
 230   {
 231    "cell_type": "code",
 232    "execution_count": 16,
 233    "metadata": {
 234     "collapsed": true
 235    },
 236    "outputs": [],
 237    "source": [
 238     "destination_values = {'Almaty': 2.0, 'Brorfelde': 0.9, 'Estacada': 0.4, 'Jayuya': 0.6, 'Karlukovo': 2.2, \n",
 239     "                      'Morgantown': 2.9,'Nordkapp': 1.5, 'Nullarbor': 2.2, \n",
 240     "                      'Puente-Laguna-Garzonkuala-Penyu': 0.4, 'Uzupis': 0.9}"
 241    ]
 242   },
 243   {
 244    "cell_type": "code",
 245    "execution_count": 17,
 246    "metadata": {
 247     "collapsed": true
 248    },
 249    "outputs": [],
 250    "source": [
 251     "def value_of_destination(name):\n",
 252     "    if name in destination_values:\n",
 253     "        return destination_values[name]\n",
 254     "    else:\n",
 255     "        return 1"
 256    ]
 257   },
 258   {
 259    "cell_type": "code",
 260    "execution_count": 18,
 261    "metadata": {
 262     "collapsed": true
 263    },
 264    "outputs": [],
 265    "source": [
 266     "def value_of_holiday(holiday):\n",
 267     "    hid, cost, destination, duration = tuple(holiday)\n",
 268     "    value = value_of_destination(destination) * float(duration) / int(cost)\n",
 269     "    return value"
 270    ]
 271   },
 272   {
 273    "cell_type": "code",
 274    "execution_count": 19,
 275    "metadata": {},
 276    "outputs": [
 277     {
 278      "data": {
 279       "text/plain": [
 280        "'ee064e1e2ea'"
 281       ]
 282      },
 283      "execution_count": 19,
 284      "metadata": {},
 285      "output_type": "execute_result"
 286     }
 287    ],
 288    "source": [
 289     "best_holiday = ''\n",
 290     "best_value = 0\n",
 291     "\n",
 292     "for h in affordable_holidays:\n",
 293     "    if value_of_holiday(h) > best_value:\n",
 294     "        best_value = value_of_holiday(h)\n",
 295     "        best_holiday = h[0]\n",
 296     "        \n",
 297     "best_holiday"
 298    ]
 299   },
 300   {
 301    "cell_type": "markdown",
 302    "metadata": {},
 303    "source": [
 304     "## Smart-alec solution"
 305    ]
 306   },
 307   {
 308    "cell_type": "code",
 309    "execution_count": 20,
 310    "metadata": {},
 311    "outputs": [
 312     {
 313      "data": {
 314       "text/plain": [
 315        "'ee064e1e2ea'"
 316       ]
 317      },
 318      "execution_count": 20,
 319      "metadata": {},
 320      "output_type": "execute_result"
 321     }
 322    ],
 323    "source": [
 324     "# Right answer\n",
 325     "max(affordable_holidays, key=value_of_holiday)[0]"
 326    ]
 327   },
 328   {
 329    "cell_type": "code",
 330    "execution_count": 21,
 331    "metadata": {},
 332    "outputs": [
 333     {
 334      "data": {
 335       "text/plain": [
 336        "'c86e2e5826'"
 337       ]
 338      },
 339      "execution_count": 21,
 340      "metadata": {},
 341      "output_type": "execute_result"
 342     }
 343    ],
 344    "source": [
 345     "# Answer if you don't filter by affordability\n",
 346     "max(holidays, key=value_of_holiday)[0]"
 347    ]
 348   },
 349   {
 350    "cell_type": "code",
 351    "execution_count": 23,
 352    "metadata": {},
 353    "outputs": [
 354     {
 355      "data": {
 356       "text/plain": [
 357        "'f60e203aaaf9'"
 358       ]
 359      },
 360      "execution_count": 23,
 361      "metadata": {},
 362      "output_type": "execute_result"
 363     }
 364    ],
 365    "source": [
 366     "# Answer if you don't scale by perceived value\n",
 367     "max(affordable_holidays, key=lambda h: float(h[3]) / float(h[1]))[0]"
 368    ]
 369   },
 370   {
 371    "cell_type": "code",
 372    "execution_count": 22,
 373    "metadata": {},
 374    "outputs": [
 375     {
 376      "data": {
 377       "text/plain": [
 378        "'f60e203aaaf9'"
 379       ]
 380      },
 381      "execution_count": 22,
 382      "metadata": {},
 383      "output_type": "execute_result"
 384     }
 385    ],
 386    "source": [
 387     "# Answer if you don't scale by perceived value, AND don't filter by affordability\n",
 388     "max(holidays, key=lambda h: float(h[3]) / float(h[1]))[0]"
 389    ]
 390   }
 391  ],
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