tutorial_python_fundamentals.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "id": "1150182d",
   "metadata": {},
   "source": [
    "# Python Fundamentals"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "0de0f3eb",
   "metadata": {},
   "source": [
    "### Invoking Python\n",
    "\n",
    "There are three main ways to use Python.\n",
    "\n",
    "1. By running a Python file, e.g. python myscript.py\n",
    "2. Through an interactive console (Python interpreter or iPython shell)\n",
    "3. In an interactive notebook (e.g. Jupyter)\n",
    "\n",
    "In this course, we will mostly be interacting with Python via Jupyter notebooks.\n"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "a004b267",
   "metadata": {},
   "source": [
    "### Basic Variables: Numbers and String"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "id": "2db9d987",
   "metadata": {},
   "outputs": [],
   "source": [
    "# comments are anything that comes after the \"#\" symbol\n",
    "a = 1       # assign 1 to variable a\n",
    "b = \"hello\" # assign \"hello\" to variable b"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "6b5720f5",
   "metadata": {},
   "source": [
    "The following identifiers are used as reserved words, or keywords of the language, and cannot be used as ordinary identifiers. They must be spelled exactly as written here:"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "9589db6e",
   "metadata": {},
   "source": [
    "    False      class      finally    is         return\n",
    "    None       continue   for        lambda     try\n",
    "    True       def        from       nonlocal   while\n",
    "    and        del        global     not        with\n",
    "    as         elif       if         or         yield\n",
    "    assert     else       import     pass\n",
    "    break      except     in         raise\n"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "fc6ada65",
   "metadata": {},
   "source": [
    "Additionally, the following a built in functions which are always available in your namespace once you open a Python interpreter"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "ec629429",
   "metadata": {},
   "source": [
    "    abs() dict() help() min() setattr() all() dir() hex() next() slice() any()\n",
    "    divmod() id() object() sorted() ascii() enumerate() input() oct() staticmethod()\n",
    "    bin() eval() int() open() str() bool() exec() isinstance() ord() sum() bytearray()\n",
    "    filter() issubclass() pow() super() bytes() float() iter() print() tuple()\n",
    "    callable() format() len() property() type() chr() frozenset() list() range()\n",
    "    vars() classmethod() getattr() locals() repr() zip() compile() globals() map()\n",
    "    reversed() __import__() complex() hasattr() max() round() delattr() hash()\n",
    "    memoryview() set()\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "id": "0c4c2d06",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "1\n",
      "hello\n",
      "1 hello\n"
     ]
    }
   ],
   "source": [
    "# how to we see our variables?\n",
    "print(a)\n",
    "print(b)\n",
    "print(a,b)\n",
    "\n"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "ecd72ca7",
   "metadata": {},
   "source": [
    "All variables are objects. Every object has a type (class). To find out what type your variables are"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "id": "89510432",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "<class 'int'>\n",
      "<class 'str'>\n"
     ]
    }
   ],
   "source": [
    "print(type(a))\n",
    "print(type(b))\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "id": "2e930ea5",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "str"
      ]
     },
     "execution_count": 7,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# as a shortcut, iPython notebooks will automatically print whatever is on the last line\n",
    "type(b)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "id": "8b40d54a",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "True\n",
      "False\n"
     ]
    }
   ],
   "source": [
    "# we can check for the type of an object\n",
    "print(type(a) is int)\n",
    "print(type(a) is str)\n",
    "\n"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "f95a0d7b",
   "metadata": {},
   "source": [
    "Different objects attributes and methods, which can be accessed via the syntax variable.method"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "id": "2336c376",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "<function str.capitalize>"
      ]
     },
     "execution_count": 9,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# this returns the method itself\n",
    "b.capitalize\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "id": "8cd6714f",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'Hello'"
      ]
     },
     "execution_count": 10,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# this calls the method\n",
    "b.capitalize()\n",
    "# there are lots of other methods\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "id": "8139f7c7",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "helloWorld\n",
      "3\n"
     ]
    },
    {
     "ename": "TypeError",
     "evalue": "unsupported operand type(s) for +: 'int' and 'str'",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[0;31mTypeError\u001b[0m                                 Traceback (most recent call last)",
      "\u001b[0;32m<ipython-input-11-addc0864a5f0>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m\u001b[0m\n\u001b[1;32m      3\u001b[0m \u001b[0mprint\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mb\u001b[0m \u001b[0;34m+\u001b[0m \u001b[0mc\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m      4\u001b[0m \u001b[0mprint\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0ma\u001b[0m \u001b[0;34m+\u001b[0m \u001b[0;36m2\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m----> 5\u001b[0;31m \u001b[0mprint\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0ma\u001b[0m \u001b[0;34m+\u001b[0m \u001b[0mb\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m\u001b[1;32m      6\u001b[0m \u001b[0;34m\u001b[0m\u001b[0m\n",
      "\u001b[0;31mTypeError\u001b[0m: unsupported operand type(s) for +: 'int' and 'str'"
     ]
    }
   ],
   "source": [
    "# binary operations act differently on different types of objects\n",
    "c = 'World'\n",
    "print(b + c)\n",
    "print(a + 2)\n",
    "print(a + b)\n",
    "\n"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "79eaa57b",
   "metadata": {},
   "source": [
    "### Math\n",
    "\n",
    "Basic arithmetic and boolean logic is part of the core Python library."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "id": "fb993503",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "-3"
      ]
     },
     "execution_count": 12,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# addition / subtraction\n",
    "1+1-5\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "id": "fe285ba6",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "50"
      ]
     },
     "execution_count": 13,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# multiplication\n",
    "5 * 10\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "id": "1ee797fa",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "0.5"
      ]
     },
     "execution_count": 14,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# division\n",
    "1/2\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "id": "507584f8",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "float"
      ]
     },
     "execution_count": 15,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# that was automatically converted to a float\n",
    "type(1/2)\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "id": "cada8b3c",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "16"
      ]
     },
     "execution_count": 16,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# exponentiation\n",
    "2**4\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 17,
   "id": "57004ff2",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "1"
      ]
     },
     "execution_count": 17,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# rounding\n",
    "round(9/10)\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "id": "9df9b3ed",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "(-0.2+0.4j)"
      ]
     },
     "execution_count": 18,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# built in complex number support\n",
    "(1+2j) / (3-4j)\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 19,
   "id": "c73ed63d",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "True"
      ]
     },
     "execution_count": 19,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# logic\n",
    "True and True\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 20,
   "id": "5712b69d",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "False"
      ]
     },
     "execution_count": 20,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "True and False\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 21,
   "id": "04a34ce0",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "True"
      ]
     },
     "execution_count": 21,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "True or True\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 22,
   "id": "e913caaa",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "True"
      ]
     },
     "execution_count": 22,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "(not True) or (not False)\n",
    "\n"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "79e6449f",
   "metadata": {},
   "source": [
    "### Conditionals\n",
    "The first step to programming. Plus an intro to Python syntax."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 24,
   "id": "5f4990dc",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Positive Number\n"
     ]
    }
   ],
   "source": [
    "x = 100\n",
    "if x > 0:\n",
    "    print('Positive Number')\n",
    "elif x < 0:\n",
    "    print('Negative Number')\n",
    "else:\n",
    "    print ('Zero!')\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 25,
   "id": "43a66828",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Positive Number\n",
      "Huge number!\n"
     ]
    }
   ],
   "source": [
    "# indentation is MANDATORY\n",
    "# blocks are closed by indentation level\n",
    "if x > 0:\n",
    "    print('Positive Number')\n",
    "    if x >= 100:\n",
    "        print('Huge number!')\n",
    "\n"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "12d2fb05",
   "metadata": {},
   "source": [
    "### More Flow Control"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 26,
   "id": "b1875723",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "10\n"
     ]
    }
   ],
   "source": [
    "# make a loop \n",
    "count = 0\n",
    "while count < 10:\n",
    "    # bad way\n",
    "    # count = count + 1\n",
    "    # better way\n",
    "    count += 1\n",
    "print(count)\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 27,
   "id": "75c9388d",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "0\n",
      "1\n",
      "2\n",
      "3\n",
      "4\n"
     ]
    }
   ],
   "source": [
    "# use range\n",
    "for i in range(5):\n",
    "    print(i)\n",
    "\n"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "7baf5613",
   "metadata": {},
   "source": [
    "*Important point* : in Python, we always count from 0!"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 28,
   "id": "0ae172e2",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "type"
      ]
     },
     "execution_count": 28,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# what is range?\n",
    "type(range)\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 29,
   "id": "aff6eb33",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "\u001b[0;31mInit signature:\u001b[0m \u001b[0mrange\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mself\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;34m/\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;34m*\u001b[0m\u001b[0margs\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;34m**\u001b[0m\u001b[0mkwargs\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
       "\u001b[0;31mDocstring:\u001b[0m     \n",
       "range(stop) -> range object\n",
       "range(start, stop[, step]) -> range object\n",
       "\n",
       "Return an object that produces a sequence of integers from start (inclusive)\n",
       "to stop (exclusive) by step.  range(i, j) produces i, i+1, i+2, ..., j-1.\n",
       "start defaults to 0, and stop is omitted!  range(4) produces 0, 1, 2, 3.\n",
       "These are exactly the valid indices for a list of 4 elements.\n",
       "When step is given, it specifies the increment (or decrement).\n",
       "\u001b[0;31mType:\u001b[0m           type\n",
       "\u001b[0;31mSubclasses:\u001b[0m     \n"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "range?\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 30,
   "id": "8afac75d",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "dog 3\n",
      "cat 3\n",
      "fish 4\n"
     ]
    }
   ],
   "source": [
    "# iterate over a list we make up\n",
    "for pet in ['dog', 'cat', 'fish']:\n",
    "    print(pet, len(pet))\n",
    "\n"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "c9b45815",
   "metadata": {},
   "source": [
    "#### What is the thing in brackets? A list! Lists are one of the core Python data structures."
   ]
  },
  {
   "cell_type": "markdown",
   "id": "b9530d3a",
   "metadata": {},
   "source": [
    "### Lists"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 71,
   "id": "b515a394",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "list"
      ]
     },
     "execution_count": 71,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "l = ['dog', 'cat', 'fish']\n",
    "type(l)\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 33,
   "id": "e2fb02eb",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "['cat', 'dog', 'fish']"
      ]
     },
     "execution_count": 33,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# list have lots of methods\n",
    "l.sort()\n",
    "l\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 34,
   "id": "53348a1c",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[0, 1, 2, 3, 4]"
      ]
     },
     "execution_count": 34,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# we can convert a range to a list\n",
    "r = list(range(5))\n",
    "r\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 35,
   "id": "09216841",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "p: 4\n",
      "r: [0, 1, 2, 3]\n",
      "p: 3\n",
      "r: [0, 1, 2]\n",
      "p: 2\n",
      "r: [0, 1]\n",
      "p: 1\n",
      "r: [0]\n",
      "p: 0\n",
      "r: []\n"
     ]
    }
   ],
   "source": [
    "while r:\n",
    "    p = r.pop()\n",
    "    print('p:', p)\n",
    "    print('r:', r)\n",
    "\n"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "2180d6c6",
   "metadata": {},
   "source": [
    "There are many different ways to interact with lists. Exploring them is part of the fun of Python.\n",
    "\n",
    "There are many different ways to interact with lists. Exploring them is part of the fun of Python.\n",
    "\n",
    "**list.append(x)** Add an item to the end of the list. Equivalent to a[len(a):] = [x].\n",
    "\n",
    "**list.extend(L)** Extend the list by appending all the items in the given list. Equivalent to a[len(a):] = L.\n",
    "\n",
    "**list.insert(i, x)** Insert an item at a given position. The first argument is the index of the element before which to insert, so a.insert(0, x) inserts at the front of the list, and a.insert(len(a), x) is equivalent to a.append(x).\n",
    "\n",
    "**list.remove(x)** Remove the first item from the list whose value is x. It is an error if there is no such item.\n",
    "\n",
    "**list.pop([i])** Remove the item at the given position in the list, and return it. If no index is specified, a.pop() removes and returns the last item in the list. (The square brackets around the i in the method signature denote that the parameter is optional, not that you should type square brackets at that position. You will see this notation frequently in the Python Library Reference.)\n",
    "\n",
    "**list.clear()** Remove all items from the list. Equivalent to del a[:].\n",
    "\n",
    "**list.index(x)** Return the index in the list of the first item whose value is x. It is an error if there is no such item.\n",
    "\n",
    "**list.count(x)** Return the number of times x appears in the list.\n",
    "\n",
    "**list.sort()** Sort the items of the list in place.\n",
    "\n",
    "**list.reverse()** Reverse the elements of the list in place.\n",
    "\n",
    "**list.copy()** Return a shallow copy of the list. Equivalent to a[:].\n",
    "\n",
    "Don’t assume you know how list operations work!"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 36,
   "id": "ee04e539",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[0, 1, 2, 3, 4, 10, 11, 12, 13, 14]"
      ]
     },
     "execution_count": 36,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# \"add\" two lists\n",
    "x = list(range(5))\n",
    "y = list(range(10,15))\n",
    "z = x + y\n",
    "z\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 37,
   "id": "f7d689f0",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "first 0\n",
      "last 14\n",
      "first 3 [0, 1, 2]\n",
      "last 3 [12, 13, 14]\n",
      "middle, skipping every other item [10, 12, 14]\n"
     ]
    }
   ],
   "source": [
    "# access items from a list\n",
    "print('first', z[0])\n",
    "print('last', z[-1])\n",
    "print('first 3', z[:3])\n",
    "print('last 3', z[-3:])\n",
    "print('middle, skipping every other item', z[5:10:2])\n",
    "\n"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "1d2f8719",
   "metadata": {},
   "source": [
    "**MEMORIZE THIS SYNTAX!** It is central to so much of Python and often proves confusing for users coming from other languages.\n",
    "\n",
    "In terms of set notation, Python indexing is left inclusive, right exclusive. If you remember this, you will never go wrong."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 38,
   "id": "54e758bb",
   "metadata": {},
   "outputs": [
    {
     "ename": "IndexError",
     "evalue": "list index out of range",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[0;31mIndexError\u001b[0m                                Traceback (most recent call last)",
      "\u001b[0;32m<ipython-input-38-fae9506def5b>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m\u001b[0m\n\u001b[1;32m      1\u001b[0m \u001b[0;31m# that means we get an error from the following\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m      2\u001b[0m \u001b[0mN\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mlen\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mz\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m----> 3\u001b[0;31m \u001b[0mz\u001b[0m\u001b[0;34m[\u001b[0m\u001b[0mN\u001b[0m\u001b[0;34m]\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m\u001b[1;32m      4\u001b[0m \u001b[0;34m\u001b[0m\u001b[0m\n",
      "\u001b[0;31mIndexError\u001b[0m: list index out of range"
     ]
    }
   ],
   "source": [
    "# that means we get an error from the following\n",
    "N = len(z)\n",
    "z[N]\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 40,
   "id": "1febf0a5",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Isabelle\n"
     ]
    }
   ],
   "source": [
    "# this index notation also applies to strings\n",
    "name = 'Isabelle Giddy'\n",
    "print(name[:8])\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 41,
   "id": "fd2c6c4a",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "False"
      ]
     },
     "execution_count": 41,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# you can also test for the presence of items in a list\n",
    "5 in z\n",
    "\n"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "4af401ef",
   "metadata": {},
   "source": [
    "Lists are not meant for maths! They don’t have a datatype."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 42,
   "id": "b70353dc",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[0, 1, 2, 3, 'fish', 10, 11, 12, 13, 14]"
      ]
     },
     "execution_count": 42,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "z[4] = 'fish'\n",
    "z\n",
    "\n"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "d32220e2",
   "metadata": {},
   "source": [
    "Python is full of tricks for iterating and working with lists"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 43,
   "id": "9e7891ea",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[0, 1, 4, 9, 16]"
      ]
     },
     "execution_count": 43,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# a cool Python trick: list comprehension\n",
    "squares = [n**2 for n in range(5)]\n",
    "squares\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 44,
   "id": "0a0ce684",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "first: 0 second: 10\n",
      "first: 1 second: 11\n",
      "first: 2 second: 12\n",
      "first: 3 second: 13\n",
      "first: 4 second: 14\n"
     ]
    }
   ],
   "source": [
    "# iterate over two lists together uzing zip\n",
    "for item1, item2 in zip(x,y):\n",
    "    print('first:', item1, 'second:', item2)\n",
    "\n"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "e293a4dc",
   "metadata": {},
   "source": [
    "### Other Data Structures\n",
    "\n",
    "We are almost there. We have the building blocks we need to do basic programming. But Python has some other data structures we need to learn about.\n",
    "\n",
    "### Tuples\n",
    "\n",
    "Tuples are similar to lists, but they are immutable—they can’t be extended or modified. What is the point of this? Generally speaking: to pack together inhomogeneous data. Tuples can then be unpacked and distributed by other parts of your code.\n",
    "\n",
    "Tuples may seem confusing at first, but with time you will come to appreciate them."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 47,
   "id": "5ba23c92",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "tuple"
      ]
     },
     "execution_count": 47,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# tuples are created with parentheses, or just commas\n",
    "a = ('Isabelle', 31, True)\n",
    "b = 'Seb', 23, False\n",
    "type(b)\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 48,
   "id": "da9cf1e9",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "31\n"
     ]
    }
   ],
   "source": [
    "# can be indexed like arrays\n",
    "print(a[1]) # not the first element!\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 49,
   "id": "52cf4dc3",
   "metadata": {},
   "outputs": [],
   "source": [
    "# and they can be unpacked\n",
    "name, age, status = a\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 53,
   "id": "ca58d54b",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'Isabelle'"
      ]
     },
     "execution_count": 53,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "name"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "26c807d6",
   "metadata": {},
   "source": [
    "### Dictionaries\n",
    "\n",
    "This is an extremely useful data structure. It maps **keys** to **values**.\n",
    "\n",
    "Dictionaries are unordered!"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 54,
   "id": "404ff96b",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "{'name': 'Seb', 'age': 23}"
      ]
     },
     "execution_count": 54,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# different ways to create dictionaries\n",
    "d = {'name': 'Isabelle', 'age': 31}\n",
    "e = dict(name='Seb', age=23)\n",
    "e\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 55,
   "id": "d07a8dce",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'Isabelle'"
      ]
     },
     "execution_count": 55,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# access a value\n",
    "d['name']\n",
    "\n"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "107ba117",
   "metadata": {},
   "source": [
    "Square brackets [...] are Python for “get item” in many different contexts."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 56,
   "id": "da52c6bf",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "True\n",
      "False\n"
     ]
    }
   ],
   "source": [
    "# test for the presence of a key\n",
    "print('age' in d)\n",
    "print('height' in e)\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 57,
   "id": "c9b3eb43",
   "metadata": {},
   "outputs": [
    {
     "ename": "KeyError",
     "evalue": "'height'",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[0;31mKeyError\u001b[0m                                  Traceback (most recent call last)",
      "\u001b[0;32m<ipython-input-57-fc3cba86f0ae>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m\u001b[0m\n\u001b[1;32m      1\u001b[0m \u001b[0;31m# try to access a non-existant key\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m----> 2\u001b[0;31m \u001b[0md\u001b[0m\u001b[0;34m[\u001b[0m\u001b[0;34m'height'\u001b[0m\u001b[0;34m]\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m\u001b[1;32m      3\u001b[0m \u001b[0;34m\u001b[0m\u001b[0m\n",
      "\u001b[0;31mKeyError\u001b[0m: 'height'"
     ]
    }
   ],
   "source": [
    "# try to access a non-existant key\n",
    "d['height']\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 61,
   "id": "b7054a74",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "{'name': 'Isabelle', 'age': 31, 'height': (5, 3), 99: 'ninety nine'}"
      ]
     },
     "execution_count": 61,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# add a new key\n",
    "d['height'] = (5,3) # a tuple\n",
    "d\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 62,
   "id": "a9301f6a",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "{'name': 'Isabelle', 'age': 31, 'height': (5, 3), 99: 'ninety nine'}"
      ]
     },
     "execution_count": 62,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# keys don't have to be strings\n",
    "d[99] = 'ninety nine'\n",
    "d\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 67,
   "id": "84e060f6",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "name Isabelle\n",
      "age 31\n",
      "height (5, 3)\n",
      "99 ninety nine\n"
     ]
    }
   ],
   "source": [
    "# iterate over keys\n",
    "for k in d:\n",
    "    print(k, d[k])\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 70,
   "id": "a2468f26",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "name Isabelle\n",
      "age 31\n",
      "height (5, 3)\n",
      "99 ninety nine\n"
     ]
    }
   ],
   "source": [
    "# better way\n",
    "for key, val in d.items():\n",
    "    print(key, val)\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "9d5fd2b2",
   "metadata": {},
   "outputs": [],
   "source": []
  }
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