02-array-seq/array-seq.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Chapter 2 — An Array of Sequences\n",
    "\n",
    "**Sections with code snippets in this chapter:**\n",
    "\n",
    "* [List Comprehensions and Generator Expressions](#List-Comprehensions-and-Generator-Expressions)\n",
    "* [Tuples Are Not Just Immutable Lists](#Tuples-Are-Not-Just-Immutable-Lists)\n",
    "* [Unpacking sequences and iterables](#Unpacking-sequences-and-iterables)\n",
    "* [Pattern Matching with Sequences](#Pattern-Matching-with-Sequences)\n",
    "* [Slicing](#Slicing)\n",
    "* [Using + and * with Sequences](#Using-+-and-*-with-Sequences)\n",
    "* [Augmented Assignment with Sequences](#Augmented-Assignment-with-Sequences)\n",
    "* [list.sort and the sorted Built-In Function](#list.sort-and-the-sorted-Built-In-Function)\n",
    "* [When a List Is Not the Answer](#When-a-List-Is-Not-the-Answer)\n",
    "* [Memory Views](#Memory-Views)\n",
    "* [NumPy and SciPy](#NumPy-and-SciPy)\n",
    "* [Deques and Other Queues](#Deques-and-Other-Queues)\n",
    "* [Soapbox](#Soapbox)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## List Comprehensions and Generator Expressions"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "#### Example 2-1. Build a list of Unicode codepoints from a string"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "[36, 162, 163, 165, 8364, 164]"
     },
     "execution_count": 1,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "symbols = '$¢£¥€¤'\n",
    "codes = []\n",
    "\n",
    "for symbol in symbols:\n",
    "    codes.append(ord(symbol))\n",
    "\n",
    "codes"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "#### Example 2-2. Build a list of Unicode codepoints from a string, using a listcomp"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "[36, 162, 163, 165, 8364, 164]"
     },
     "execution_count": 2,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "symbols = '$¢£¥€¤'\n",
    "\n",
    "codes = [ord(symbol) for symbol in symbols]\n",
    "\n",
    "codes"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "#### Box: Listcomps No Longer Leak Their Variables"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "'ABC'"
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "x = 'ABC'\n",
    "codes = [ord(x) for x in x]\n",
    "x"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "[65, 66, 67]"
     },
     "execution_count": 4,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "codes"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "outputs": [
    {
     "data": {
      "text/plain": "67"
     },
     "execution_count": 5,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "codes = [last := ord(c) for c in x]\n",
    "last"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%%\n"
    }
   }
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "#### Example 2-3. The same list built by a listcomp and a map/filter composition"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "[162, 163, 165, 8364, 164]"
     },
     "execution_count": 6,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "symbols = '$¢£¥€¤'\n",
    "beyond_ascii = [ord(s) for s in symbols if ord(s) > 127]\n",
    "beyond_ascii"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "[162, 163, 165, 8364, 164]"
     },
     "execution_count": 7,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "beyond_ascii = list(filter(lambda c: c > 127, map(ord, symbols)))\n",
    "beyond_ascii"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "#### Example 2-4. Cartesian product using a list comprehension"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "[('black', 'S'),\n ('black', 'M'),\n ('black', 'L'),\n ('white', 'S'),\n ('white', 'M'),\n ('white', 'L')]"
     },
     "execution_count": 8,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "colors = ['black', 'white']\n",
    "sizes = ['S', 'M', 'L']\n",
    "tshirts = [(color, size) for color in colors for size in sizes]\n",
    "tshirts"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "('black', 'S')\n",
      "('black', 'M')\n",
      "('black', 'L')\n",
      "('white', 'S')\n",
      "('white', 'M')\n",
      "('white', 'L')\n"
     ]
    }
   ],
   "source": [
    "for color in colors:\n",
    "    for size in sizes:\n",
    "        print((color, size))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "[('black', 'S'),\n ('black', 'M'),\n ('black', 'L'),\n ('white', 'S'),\n ('white', 'M'),\n ('white', 'L')]"
     },
     "execution_count": 10,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "shirts = [(color, size) for size in sizes\n",
    "          for color in colors]\n",
    "tshirts"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "#### Example 2-5. Initializing a tuple and an array from a generator expression"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "(36, 162, 163, 165, 8364, 164)"
     },
     "execution_count": 11,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "symbols = '$¢£¥€¤'\n",
    "tuple(ord(symbol) for symbol in symbols)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "array('I', [36, 162, 163, 165, 8364, 164])"
     },
     "execution_count": 12,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "import array\n",
    "\n",
    "array.array('I', (ord(symbol) for symbol in symbols))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "#### Example 2-6. Cartesian product in a generator expression"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "black S\n",
      "black M\n",
      "black L\n",
      "white S\n",
      "white M\n",
      "white L\n"
     ]
    }
   ],
   "source": [
    "colors = ['black', 'white']\n",
    "sizes = ['S', 'M', 'L']\n",
    "\n",
    "for tshirt in ('%s %s' % (c, s) for c in colors for s in sizes):\n",
    "    print(tshirt)"
   ]
  },
  {
   "cell_type": "markdown",
   "source": [
    "## Tuples Are Not Just Immutable Lists"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%% md\n"
    }
   },
   "execution_count": 73
  },
  {
   "cell_type": "markdown",
   "source": [
    "#### Example 2-7. Tuples used as records"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%% md\n"
    }
   }
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "BRA/CE342567\n",
      "ESP/XDA205856\n",
      "USA/31195855\n"
     ]
    }
   ],
   "source": [
    "lax_coordinates = (33.9425, -118.408056)\n",
    "city, year, pop, chg, area = ('Tokyo', 2003, 32_450, 0.66, 8014)\n",
    "traveler_ids = [('USA', '31195855'), ('BRA', 'CE342567'), ('ESP', 'XDA205856')]\n",
    "\n",
    "for passport in sorted(traveler_ids):\n",
    "    print('%s/%s' % passport)"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%%\n"
    }
   }
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "USA\n",
      "BRA\n",
      "ESP\n"
     ]
    }
   ],
   "source": [
    "for country, _ in traveler_ids:\n",
    "    print(country)"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%%\n"
    }
   }
  },
  {
   "cell_type": "markdown",
   "source": [
    "### Tuples as Immutable Lists"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%% md\n"
    }
   }
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "outputs": [
    {
     "data": {
      "text/plain": "True"
     },
     "execution_count": 16,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "a = (10, 'alpha', [1, 2])\n",
    "b = (10, 'alpha', [1, 2])\n",
    "a == b"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%%\n"
    }
   }
  },
  {
   "cell_type": "code",
   "execution_count": 17,
   "outputs": [
    {
     "data": {
      "text/plain": "False"
     },
     "execution_count": 17,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "b[-1].append(99)\n",
    "a == b"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%%\n"
    }
   }
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "outputs": [
    {
     "data": {
      "text/plain": "(10, 'alpha', [1, 2, 99])"
     },
     "execution_count": 18,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "b"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%%\n"
    }
   }
  },
  {
   "cell_type": "code",
   "execution_count": 19,
   "outputs": [
    {
     "data": {
      "text/plain": "True"
     },
     "execution_count": 19,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "def fixed(o):\n",
    "    try:\n",
    "        hash(o)\n",
    "    except TypeError:\n",
    "        return False\n",
    "    return True\n",
    "\n",
    "\n",
    "tf = (10, 'alpha', (1, 2))  # Contains no mutable items\n",
    "tm = (10, 'alpha', [1, 2])  # Contains a mutable item (list)\n",
    "fixed(tf)"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%%\n"
    }
   }
  },
  {
   "cell_type": "code",
   "execution_count": 20,
   "outputs": [
    {
     "data": {
      "text/plain": "False"
     },
     "execution_count": 20,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "fixed(tm)"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%%\n"
    }
   }
  },
  {
   "cell_type": "markdown",
   "source": [
    "## Unpacking sequences and iterables"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%% md\n"
    }
   }
  },
  {
   "cell_type": "code",
   "execution_count": 21,
   "outputs": [
    {
     "data": {
      "text/plain": "33.9425"
     },
     "execution_count": 21,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "lax_coordinates = (33.9425, -118.408056)\n",
    "latitude, longitude = lax_coordinates  # unpacking\n",
    "latitude"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%%\n"
    }
   }
  },
  {
   "cell_type": "code",
   "execution_count": 22,
   "outputs": [
    {
     "data": {
      "text/plain": "-118.408056"
     },
     "execution_count": 22,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "longitude"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%%\n"
    }
   }
  },
  {
   "cell_type": "code",
   "execution_count": 23,
   "outputs": [
    {
     "data": {
      "text/plain": "(2, 4)"
     },
     "execution_count": 23,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "divmod(20, 8)"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%%\n"
    }
   }
  },
  {
   "cell_type": "code",
   "execution_count": 24,
   "outputs": [
    {
     "data": {
      "text/plain": "(2, 4)"
     },
     "execution_count": 24,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "t = (20, 8)\n",
    "divmod(*t)"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%%\n"
    }
   }
  },
  {
   "cell_type": "code",
   "execution_count": 25,
   "outputs": [
    {
     "data": {
      "text/plain": "(2, 4)"
     },
     "execution_count": 25,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "quotient, remainder = divmod(*t)\n",
    "quotient, remainder"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%%\n"
    }
   }
  },
  {
   "cell_type": "code",
   "execution_count": 26,
   "outputs": [
    {
     "data": {
      "text/plain": "'id_rsa.pub'"
     },
     "execution_count": 26,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "import os\n",
    "\n",
    "_, filename = os.path.split('/home/luciano/.ssh/id_rsa.pub')\n",
    "filename"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%%\n"
    }
   }
  },
  {
   "cell_type": "markdown",
   "source": [
    "### Using * to grab excess items"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%% md\n"
    }
   }
  },
  {
   "cell_type": "code",
   "execution_count": 27,
   "outputs": [
    {
     "data": {
      "text/plain": "(0, 1, [2, 3, 4])"
     },
     "execution_count": 27,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "a, b, *rest = range(5)\n",
    "a, b, rest"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%%\n"
    }
   }
  },
  {
   "cell_type": "code",
   "execution_count": 28,
   "outputs": [
    {
     "data": {
      "text/plain": "(0, 1, [2])"
     },
     "execution_count": 28,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "a, b, *rest = range(3)\n",
    "a, b, rest"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%%\n"
    }
   }
  },
  {
   "cell_type": "code",
   "execution_count": 29,
   "outputs": [
    {
     "data": {
      "text/plain": "(0, 1, [])"
     },
     "execution_count": 29,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "a, b, *rest = range(2)\n",
    "a, b, rest"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%%\n"
    }
   }
  },
  {
   "cell_type": "code",
   "execution_count": 30,
   "outputs": [
    {
     "data": {
      "text/plain": "(0, [1, 2], 3, 4)"
     },
     "execution_count": 30,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "a, *body, c, d = range(5)\n",
    "a, body, c, d"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%%\n"
    }
   }
  },
  {
   "cell_type": "code",
   "execution_count": 31,
   "outputs": [
    {
     "data": {
      "text/plain": "([0, 1], 2, 3, 4)"
     },
     "execution_count": 31,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "*head, b, c, d = range(5)\n",
    "head, b, c, d"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%%\n"
    }
   }
  },
  {
   "cell_type": "markdown",
   "source": [
    "### Unpacking with * in function calls and sequence literals"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%% md\n"
    }
   }
  },
  {
   "cell_type": "code",
   "execution_count": 32,
   "outputs": [
    {
     "data": {
      "text/plain": "(1, 2, 3, 4, (5, 6))"
     },
     "execution_count": 32,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "def fun(a, b, c, d, *rest):\n",
    "    return a, b, c, d, rest\n",
    "\n",
    "\n",
    "fun(*[1, 2], 3, *range(4, 7))"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%%\n"
    }
   }
  },
  {
   "cell_type": "code",
   "execution_count": 33,
   "outputs": [
    {
     "data": {
      "text/plain": "(0, 1, 2, 3, 4)"
     },
     "execution_count": 33,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "*range(4), 4"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%%\n"
    }
   }
  },
  {
   "cell_type": "code",
   "execution_count": 34,
   "outputs": [
    {
     "data": {
      "text/plain": "[0, 1, 2, 3, 4]"
     },
     "execution_count": 34,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "[*range(4), 4]"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%%\n"
    }
   }
  },
  {
   "cell_type": "code",
   "execution_count": 35,
   "outputs": [
    {
     "data": {
      "text/plain": "{0, 1, 2, 3, 4, 5, 6, 7}"
     },
     "execution_count": 35,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "{*range(4), 4, *(5, 6, 7)}"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%%\n"
    }
   }
  },
  {
   "cell_type": "markdown",
   "source": [
    "### Nested unpacking\n",
    "#### Example 2-8. Unpacking nested tuples to access the longitude\n",
    "\n",
    "[02-array-seq/metro_lat_lon.py](02-array-seq/metro_lat_lon.py)"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%% md\n"
    }
   }
  },
  {
   "cell_type": "markdown",
   "source": [
    "## Pattern Matching with Sequences\n",
    "#### Example 2-9. Method from an imaginary Robot class"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%% md\n"
    }
   }
  },
  {
   "cell_type": "code",
   "execution_count": 36,
   "outputs": [],
   "source": [
    "# def handle_command(self, message):\n",
    "#     match message:\n",
    "#         case ['BEEPER', frequency, times]:\n",
    "#             self.beep(times, frequency)\n",
    "#         case ['NECK', angle]:\n",
    "#             self.rotate_neck(angle)\n",
    "#         case ['LED', ident, intensity]:\n",
    "#             self.leds[ident].set_brightness(ident, intensity)\n",
    "#         case ['LED', ident, red, green, blue]:\n",
    "#             self.leds[ident].set_color(ident, red, green, blue)\n",
    "#         case _:\n",
    "#             raise InvalidCommand(message)"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%%\n"
    }
   }
  },
  {
   "cell_type": "markdown",
   "source": [
    "#### Example 2-10. Destructuring nested tuples—requires Python ≥ 3.10.\n",
    "[02-array-seq/match_lat_lon.py](02-array-seq/match_lat_lon.py)"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%% md\n"
    }
   }
  },
  {
   "cell_type": "code",
   "execution_count": 37,
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "                |  latitude | longitude\n",
      "Mexico City     |   19.4333 |  -99.1333\n",
      "New York-Newark |   40.8086 |  -74.0204\n",
      "São Paulo       |  -23.5478 |  -46.6358\n"
     ]
    }
   ],
   "source": [
    "metro_areas = [\n",
    "    ('Tokyo', 'JP', 36.933, (35.689722, 139.691667)),\n",
    "    ('Delhi NCR', 'IN', 21.935, (28.613889, 77.208889)),\n",
    "    ('Mexico City', 'MX', 20.142, (19.433333, -99.133333)),\n",
    "    ('New York-Newark', 'US', 20.104, (40.808611, -74.020386)),\n",
    "    ('São Paulo', 'BR', 19.649, (-23.547778, -46.635833)),\n",
    "]\n",
    "\n",
    "def main():\n",
    "    print(f'{\"\":15} | {\"latitude\":>9} | {\"longitude\":>9}')\n",
    "    for record in metro_areas:\n",
    "        match record:\n",
    "            case [name, _, _, (lat, lon)] if lon <= 0:\n",
    "                print(f'{name:15} | {lat:9.4f} | {lon:9.4f}')\n",
    "main()"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%%\n"
    }
   }
  },
  {
   "cell_type": "markdown",
   "source": [],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%% md\n"
    }
   }
  },
  {
   "cell_type": "markdown",
   "source": [
    "### Pattern Matching Sequences in an Interpreter\n",
    "#### Example 2-11. Matching patterns without match/case.\n",
    "[02-array-seq/lispy/py3.9/lis.py](02-array-seq/lispy/py3.9/lis.py)"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%% md\n"
    }
   }
  },
  {
   "cell_type": "markdown",
   "source": [
    "#### Example 2-12. Pattern matching with match/case—requires Python ≥ 3.10.\n",
    "[02-array-seq/lispy/py3.10/lis.py](02-array-seq/lispy/py3.10/lis.py)"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%% md\n"
    }
   }
  },
  {
   "cell_type": "markdown",
   "source": [],
   "metadata": {
    "collapsed": false
   }
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Slicing"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Why Slices and Range Exclude the Last Item"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 38,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "[10, 20]"
     },
     "execution_count": 38,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "l = [10, 20, 30, 40, 50, 60]\n",
    "\n",
    "l[:2]  # split at 2"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 39,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "[30, 40, 50, 60]"
     },
     "execution_count": 39,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "l[2:]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 40,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "[10, 20, 30]"
     },
     "execution_count": 40,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "l[:3]  # split at 3"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 41,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "[40, 50, 60]"
     },
     "execution_count": 41,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "l[3:]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Slice Objects"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 42,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "'bye'"
     },
     "execution_count": 42,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "s = 'bicycle'\n",
    "s[::3]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 43,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "'elcycib'"
     },
     "execution_count": 43,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "s[::-1]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 44,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "'eccb'"
     },
     "execution_count": 44,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "s[::-2]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "#### Example 2-13. Line items from a flat-file invoice"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 45,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "    $17.50   imoroni PiBrella                  \n",
      "     $4.95   mm Tactile Switch x20             \n",
      "    $28.00   anavise Jr. - PV-201              \n",
      "    $34.95   iTFT Mini Kit 320x240             \n",
      " \n"
     ]
    }
   ],
   "source": [
    "invoice = \"\"\"\n",
    "0.....6.................................40........52...55........\n",
    "1909 Pimoroni PiBrella                      $17.50    3    $52.50\n",
    "1489 6mm Tactile Switch x20                  $4.95    2    $9.90\n",
    "1510 Panavise Jr. - PV-201                  $28.00    1    $28.00\n",
    "1601 PiTFT Mini Kit 320x240                 $34.95    1    $34.95\n",
    "\"\"\"\n",
    "\n",
    "SKU = slice(0, 6)\n",
    "DESCRIPTION = slice(6, 40)\n",
    "UNIT_PRICE = slice(40, 52)\n",
    "QUANTITY = slice(52, 55)\n",
    "ITEM_TOTAL = slice(55, None)\n",
    "\n",
    "line_items = invoice.split('\\n')[2:]\n",
    "\n",
    "for item in line_items:\n",
    "    print(item[UNIT_PRICE], item[DESCRIPTION])"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Assigning to Slices"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 46,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]"
     },
     "execution_count": 46,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "l = list(range(10))\n",
    "l"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 47,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "[0, 1, 20, 30, 5, 6, 7, 8, 9]"
     },
     "execution_count": 47,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "l[2:5] = [20, 30]\n",
    "l"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 48,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "[0, 1, 20, 30, 5, 8, 9]"
     },
     "execution_count": 48,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "del l[5:7]\n",
    "l"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 49,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "[0, 1, 20, 11, 5, 22, 9]"
     },
     "execution_count": 49,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "l[3::2] = [11, 22]\n",
    "l"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "By design, this example raises an exception::"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 50,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "TypeError('can only assign an iterable')\n"
     ]
    }
   ],
   "source": [
    "try:\n",
    "    l[2:5] = 100\n",
    "except TypeError as e:\n",
    "    print(repr(e))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 51,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "[0, 1, 100, 22, 9]"
     },
     "execution_count": 51,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "l[2:5] = [100]\n",
    "l"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Using + and * with Sequences"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 52,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "[1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3]"
     },
     "execution_count": 52,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "l = [1, 2, 3]\n",
    "l * 5"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 53,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "'abcdabcdabcdabcdabcd'"
     },
     "execution_count": 53,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "5 * 'abcd'"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Building Lists of Lists"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "#### Example 2-14. A list with three lists of length 3 can represent a tic-tac-toe board"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 54,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "[['_', '_', '_'], ['_', '_', '_'], ['_', '_', '_']]"
     },
     "execution_count": 54,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "board = [['_'] * 3 for i in range(3)]\n",
    "board"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 55,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "[['_', '_', '_'], ['_', '_', 'X'], ['_', '_', '_']]"
     },
     "execution_count": 55,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "board[1][2] = 'X'\n",
    "board"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "#### Example 2-15. A list with three references to the same list is useless"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 56,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "[['_', '_', '_'], ['_', '_', '_'], ['_', '_', '_']]"
     },
     "execution_count": 56,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "weird_board = [['_'] * 3] * 3\n",
    "weird_board"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 57,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "[['_', '_', 'O'], ['_', '_', 'O'], ['_', '_', 'O']]"
     },
     "execution_count": 57,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "weird_board[1][2] = 'O'\n",
    "weird_board"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "#### Explanation"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 58,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "[['_', '_', '_'], ['_', '_', '_'], ['_', '_', '_']]"
     },
     "execution_count": 58,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "board = []\n",
    "for i in range(3):\n",
    "    row = ['_'] * 3\n",
    "    board.append(row)\n",
    "board"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 59,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "[['_', '_', '_'], ['_', '_', '_'], ['X', '_', '_']]"
     },
     "execution_count": 59,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "board[2][0] = 'X'\n",
    "board"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Augmented Assignment with Sequences"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 60,
   "metadata": {},
   "outputs": [],
   "source": [
    "l = [1, 2, 3]\n",
    "idl = id(l)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 61,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "140694277263808"
     },
     "execution_count": 61,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# NBVAL_IGNORE_OUTPUT\n",
    "idl"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 62,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "[1, 2, 3, 1, 2, 3]"
     },
     "execution_count": 62,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "l *= 2\n",
    "l"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 63,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "True"
     },
     "execution_count": 63,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "id(l) == idl  # same list"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 64,
   "metadata": {},
   "outputs": [],
   "source": [
    "t = (1, 2, 3)\n",
    "idt = id(t)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 65,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "140694329335488"
     },
     "execution_count": 65,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# NBVAL_IGNORE_OUTPUT\n",
    "idt"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 66,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "False"
     },
     "execution_count": 66,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "t *= 2\n",
    "id(t) == idt  # new tuple"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### A += Assignment Puzzler\n",
    "#### Example 2-16. A riddle"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 67,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "TypeError(\"'tuple' object does not support item assignment\")\n"
     ]
    }
   ],
   "source": [
    "t = (1, 2, [30, 40])\n",
    "try:\n",
    "    t[2] += [50, 60]\n",
    "except TypeError as e:\n",
    "    print(repr(e))"
   ]
  },
  {
   "cell_type": "markdown",
   "source": [
    "#### Example 2-17. The unexpected result: item t2 is changed and an exception is raised"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%% md\n"
    }
   }
  },
  {
   "cell_type": "code",
   "execution_count": 68,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "(1, 2, [30, 40, 50, 60])"
     },
     "execution_count": 68,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "t"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "#### Example 2-18. Bytecode for the expression s[a] += b"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 69,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "  1           0 LOAD_NAME                0 (s)\n",
      "              2 LOAD_NAME                1 (a)\n",
      "              4 DUP_TOP_TWO\n",
      "              6 BINARY_SUBSCR\n",
      "              8 LOAD_NAME                2 (b)\n",
      "             10 INPLACE_ADD\n",
      "             12 ROT_THREE\n",
      "             14 STORE_SUBSCR\n",
      "             16 LOAD_CONST               0 (None)\n",
      "             18 RETURN_VALUE\n"
     ]
    }
   ],
   "source": [
    "import dis\n",
    "\n",
    "dis.dis('s[a] += b')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## list.sort and the sorted Built-In Function"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 70,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "['apple', 'banana', 'grape', 'raspberry']"
     },
     "execution_count": 70,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "fruits = ['grape', 'raspberry', 'apple', 'banana']\n",
    "sorted(fruits)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 71,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "['grape', 'raspberry', 'apple', 'banana']"
     },
     "execution_count": 71,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "fruits"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 72,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "['raspberry', 'grape', 'banana', 'apple']"
     },
     "execution_count": 72,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "sorted(fruits, reverse=True)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 73,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "['grape', 'apple', 'banana', 'raspberry']"
     },
     "execution_count": 73,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "sorted(fruits, key=len)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 74,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "['raspberry', 'banana', 'grape', 'apple']"
     },
     "execution_count": 74,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "sorted(fruits, key=len, reverse=True)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 75,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "['grape', 'raspberry', 'apple', 'banana']"
     },
     "execution_count": 75,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "fruits"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 76,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "['apple', 'banana', 'grape', 'raspberry']"
     },
     "execution_count": 76,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "fruits.sort()\n",
    "fruits"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## When a List Is Not the Answer"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Arrays"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "#### Example 2-19. Creating, saving, and loading a large array of floats"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 77,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "0.8190492979077034"
     },
     "execution_count": 77,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "from array import array\n",
    "from random import random, seed\n",
    "seed(10)  # Use seed to make the output consistent\n",
    "\n",
    "floats = array('d', (random() for i in range(10 ** 7)))\n",
    "floats[-1]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 78,
   "metadata": {},
   "outputs": [],
   "source": [
    "with open('floats.bin', 'wb') as fp:\n",
    "    floats.tofile(fp)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 79,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "0.8190492979077034"
     },
     "execution_count": 79,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "floats2 = array('d')\n",
    "\n",
    "with open('floats.bin', 'rb') as fp:\n",
    "    floats2.fromfile(fp, 10 ** 7)\n",
    "\n",
    "floats2[-1]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 80,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "True"
     },
     "execution_count": 80,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "floats2 == floats"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Memory Views"
   ]
  },
  {
   "cell_type": "markdown",
   "source": [
    "#### Example 2-20. Handling 6 bytes memory of as 1×6, 2×3, and 3×2 views"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%% md\n"
    }
   }
  },
  {
   "cell_type": "code",
   "execution_count": 81,
   "outputs": [
    {
     "data": {
      "text/plain": "[0, 1, 2, 3, 4, 5]"
     },
     "execution_count": 81,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "octets = array('B', range(6))\n",
    "m1 = memoryview(octets)\n",
    "m1.tolist()"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%%\n"
    }
   }
  },
  {
   "cell_type": "code",
   "execution_count": 82,
   "outputs": [
    {
     "data": {
      "text/plain": "[[0, 1, 2], [3, 4, 5]]"
     },
     "execution_count": 82,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "m2 = m1.cast('B', [2, 3])\n",
    "m2.tolist()"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%%\n"
    }
   }
  },
  {
   "cell_type": "code",
   "execution_count": 83,
   "outputs": [
    {
     "data": {
      "text/plain": "[[0, 1], [2, 3], [4, 5]]"
     },
     "execution_count": 83,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "m3 = m1.cast('B', [3, 2])\n",
    "m3.tolist()"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%%\n"
    }
   }
  },
  {
   "cell_type": "code",
   "execution_count": 84,
   "outputs": [
    {
     "data": {
      "text/plain": "array('B', [0, 1, 2, 33, 22, 5])"
     },
     "execution_count": 84,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "m2[1,1] = 22\n",
    "m3[1,1] = 33\n",
    "octets"
   ],
   "metadata": {
    "collapsed": false,
    "pycharm": {
     "name": "#%%\n"
    }
   }
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "#### Example 2-21. Changing the value of an 16-bit integer array item by poking one of its bytes"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 85,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "5"
     },
     "execution_count": 85,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "numbers = array('h', [-2, -1, 0, 1, 2])\n",
    "memv = memoryview(numbers)\n",
    "len(memv)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 86,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "-2"
     },
     "execution_count": 86,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "memv[0]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 87,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "[254, 255, 255, 255, 0, 0, 1, 0, 2, 0]"
     },
     "execution_count": 87,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "memv_oct = memv.cast('B')\n",
    "memv_oct.tolist()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 88,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "array('h', [-2, -1, 1024, 1, 2])"
     },
     "execution_count": 88,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "memv_oct[5] = 4\n",
    "numbers"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### NumPy"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "#### Example 2-22. Basic operations with rows and columns in a numpy.ndarray"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 89,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "array([ 0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11])"
     },
     "execution_count": 89,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "import numpy as np\n",
    "\n",
    "a = np.arange(12)\n",
    "a"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 90,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "numpy.ndarray"
     },
     "execution_count": 90,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "type(a)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 91,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "(12,)"
     },
     "execution_count": 91,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "a.shape"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 92,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "array([[ 0,  1,  2,  3],\n       [ 4,  5,  6,  7],\n       [ 8,  9, 10, 11]])"
     },
     "execution_count": 92,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "a.shape = 3, 4\n",
    "a"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 93,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "array([ 8,  9, 10, 11])"
     },
     "execution_count": 93,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "a[2]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 94,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "9"
     },
     "execution_count": 94,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "a[2, 1]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 95,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "array([1, 5, 9])"
     },
     "execution_count": 95,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "a[:, 1]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 96,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "array([[ 0,  4,  8],\n       [ 1,  5,  9],\n       [ 2,  6, 10],\n       [ 3,  7, 11]])"
     },
     "execution_count": 96,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "a.transpose()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "#### Example 2-22. Loading, saving, and vectorized operations"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 97,
   "metadata": {},
   "outputs": [],
   "source": [
    "with open('floats-1M-lines.txt', 'wt') as fp:\n",
    "    for _ in range(1_000_000):\n",
    "        fp.write(f'{random()}\\n')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 98,
   "metadata": {},
   "outputs": [],
   "source": [
    "floats = np.loadtxt('floats-1M-lines.txt')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 99,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "array([0.06078257, 0.61741189, 0.84349987])"
     },
     "execution_count": 99,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "floats[-3:]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 100,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "array([0.03039128, 0.30870594, 0.42174994])"
     },
     "execution_count": 100,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "floats *= .5\n",
    "floats[-3:]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 101,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "True"
     },
     "execution_count": 101,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "from time import perf_counter as pc\n",
    "\n",
    "t0 = pc()\n",
    "floats /= 3\n",
    "(pc() - t0) < 0.01"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 102,
   "metadata": {},
   "outputs": [],
   "source": [
    "np.save('floats-1M', floats)\n",
    "floats2 = np.load('floats-1M.npy', 'r+')\n",
    "floats2 *= 6"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 103,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "memmap([0.06078257, 0.61741189, 0.84349987])"
     },
     "execution_count": 103,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "floats2[-3:]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Deques and Other Queues"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "#### Example 2-23. Working with a deque"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 104,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "deque([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])"
     },
     "execution_count": 104,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "import collections\n",
    "\n",
    "dq = collections.deque(range(10), maxlen=10)\n",
    "dq"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 105,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "deque([7, 8, 9, 0, 1, 2, 3, 4, 5, 6])"
     },
     "execution_count": 105,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "dq.rotate(3)\n",
    "dq"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 106,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "deque([1, 2, 3, 4, 5, 6, 7, 8, 9, 0])"
     },
     "execution_count": 106,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "dq.rotate(-4)\n",
    "dq"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 107,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "deque([-1, 1, 2, 3, 4, 5, 6, 7, 8, 9])"
     },
     "execution_count": 107,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "dq.appendleft(-1)\n",
    "dq"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 108,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "deque([3, 4, 5, 6, 7, 8, 9, 11, 22, 33])"
     },
     "execution_count": 108,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "dq.extend([11, 22, 33])\n",
    "dq"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 109,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "deque([40, 30, 20, 10, 3, 4, 5, 6, 7, 8])"
     },
     "execution_count": 109,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "dq.extendleft([10, 20, 30, 40])\n",
    "dq"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Soapbox"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Mixed bag lists"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 110,
   "metadata": {},
   "outputs": [],
   "source": [
    "l = [28, 14, '28', 5, '9', '1', 0, 6, '23', 19]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 111,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "TypeError(\"'<' not supported between instances of 'str' and 'int'\")\n"
     ]
    }
   ],
   "source": [
    "try:\n",
    "    sorted(l)\n",
    "except TypeError as e:\n",
    "    print(repr(e))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Key is Brilliant"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 112,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "[0, '1', 5, 6, '9', 14, 19, '23', 28, '28']"
     },
     "execution_count": 112,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "l = [28, 14, '28', 5, '9', '1', 0, 6, '23', 19]\n",
    "\n",
    "sorted(l, key=int)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 113,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": "[0, '1', 14, 19, '23', 28, '28', 5, 6, '9']"
     },
     "execution_count": 113,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "sorted(l, key=str)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 113,
   "metadata": {},
   "outputs": [],
   "source": []
  }
 ],
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