week_06.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Dictionaries"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "{'name': 'Morty', 'age': 26}\n"
     ]
    }
   ],
   "source": [
    "# declaring a dictionary variable\n",
    "\n",
    "empty = {}  # empty dictionary\n",
    "\n",
    "person = { 'name' : 'John Smith' }    # dictionary with one key/value pair\n",
    "\n",
    "customer = {\n",
    "    'name' : 'Morty',\n",
    "    'age' : 26\n",
    "}                    # dictionary with two key/value pairs\n",
    "\n",
    "print(customer)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "John\n"
     ]
    }
   ],
   "source": [
    "# accessing dictionary information through keys\n",
    "\n",
    "person = { 'name' : 'John' }\n",
    "\n",
    "print( person['name'] )       # access information through the key"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "John\n",
      "Age is not available.\n"
     ]
    }
   ],
   "source": [
    "# using the get method to access dictionary information\n",
    "\n",
    "person = { 'name' : 'John' }\n",
    "\n",
    "print( person.get('name') )     # retrieves value of name key as before\n",
    "\n",
    "print( person.get('age', 'Age is not available.') )    # get is a secure way to retrieve information"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "baseball\n"
     ]
    }
   ],
   "source": [
    "# storing a list within a dictionary and accessing it\n",
    "\n",
    "data = { 'sports' : ['baseball', 'football', 'hockey', 'soccer'] }\n",
    "\n",
    "print( data['sports'][0] )     # first access the key, then the index"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 24,
   "metadata": {},
   "outputs": [
    {
     "ename": "ValueError",
     "evalue": "dictionary update sequence element #0 has length 8; 2 is required",
     "output_type": "error",
     "traceback": [
      "\u001b[1;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[1;31mValueError\u001b[0m                                Traceback (most recent call last)",
      "\u001b[1;32m<ipython-input-24-7378452ad479>\u001b[0m in \u001b[0;36m<module>\u001b[1;34m()\u001b[0m\n\u001b[0;32m      3\u001b[0m \u001b[0msports\u001b[0m \u001b[1;33m=\u001b[0m \u001b[1;33m[\u001b[0m \u001b[1;34m\"baseball\"\u001b[0m\u001b[1;33m,\u001b[0m \u001b[1;34m\"football\"\u001b[0m\u001b[1;33m,\u001b[0m \u001b[1;34m\"hockey\"\u001b[0m\u001b[1;33m,\u001b[0m \u001b[1;34m\"soccer\"\u001b[0m \u001b[1;33m]\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0;32m      4\u001b[0m \u001b[1;33m\u001b[0m\u001b[0m\n\u001b[1;32m----> 5\u001b[1;33m \u001b[0msports_dict\u001b[0m \u001b[1;33m=\u001b[0m \u001b[0mdict\u001b[0m\u001b[1;33m(\u001b[0m \u001b[0msports\u001b[0m \u001b[1;33m)\u001b[0m     \u001b[1;31m# will produce error, no key\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[1;31mValueError\u001b[0m: dictionary update sequence element #0 has length 8; 2 is required"
     ]
    }
   ],
   "source": [
    "# improperly storing a list within a dictionary\n",
    "\n",
    "sports = [ \"baseball\", \"football\", \"hockey\", \"soccer\" ]\n",
    "\n",
    "sports_dict = dict( sports )     # will produce error, no key"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "{'name': 'Kirsten'}\n",
      "Kirsten\n"
     ]
    }
   ],
   "source": [
    "# storing a dictionary within a list and accessing it\n",
    "\n",
    "data = ['John', 'Dennis', {'name' : 'Kirsten'}]\n",
    "\n",
    "print( data[2] )   # the dictionary is in index 2\n",
    "\n",
    "print( data[2]['name'] )    # first access the index, then access the key"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "{'2018': 108, '2017': 93}\n",
      "108\n"
     ]
    }
   ],
   "source": [
    "# storing a dictionary within a dictionary and accessing it\n",
    "\n",
    "data = {\n",
    "    'team' : 'Boston Red Sox',\n",
    "    'wins' : { '2018' : 108, '2017' : 93 }\n",
    "}\n",
    "\n",
    "print( data['wins'] )     # will output the dictionary within the wins key\n",
    "\n",
    "print( data['wins']['2018'] )    # first access the wins key, then the next key"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Working with Dictionaries"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Year: 2018\tColor: Blue\n"
     ]
    }
   ],
   "source": [
    "# adding new key/value pairs to a dictionary\n",
    "\n",
    "car = { 'year' : 2018 }\n",
    "\n",
    "car['color'] = 'Blue'\n",
    "\n",
    "print(\"Year: {}\\tColor: {}\".format(car['year'], car['color']))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Year: 2018\tColor: Red\n"
     ]
    }
   ],
   "source": [
    "# updating a value for a key/value pair that already exists\n",
    "\n",
    "car = { 'year' : 2018, 'color' : 'Blue' }\n",
    "\n",
    "car['color'] = 'Red'\n",
    "\n",
    "print(\"Year: {}\\tColor: {}\".format(car['year'], car['color']))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "{}\n"
     ]
    }
   ],
   "source": [
    "# deleting a key/value pair from a dictionary\n",
    "\n",
    "car = { 'year' : 2018 }\n",
    "\n",
    "try:\n",
    "    del car['year']\n",
    "    print(car)\n",
    "except:\n",
    "    print('That key does not exist')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "name\n",
      "John\n",
      "age\n",
      "26\n"
     ]
    }
   ],
   "source": [
    "# looping over a dictionary via the keys\n",
    "\n",
    "person = { 'name' : 'John', 'age' : 26 }\n",
    "\n",
    "for key in person.keys():\n",
    "    print(key)\n",
    "    print(person[key])   # will output the value at the current key"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "John\n",
      "26\n"
     ]
    }
   ],
   "source": [
    "# looping over a dictionary via the values\n",
    "\n",
    "person = { 'name' : 'John', 'age' : 26 }\n",
    "\n",
    "for value in person.values():\n",
    "    print(value)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "name: John\n",
      "age: 26\n"
     ]
    }
   ],
   "source": [
    "# looping over a dictionary via the key/value pair\n",
    "\n",
    "person = { 'name' : 'John', 'age' : 26 }\n",
    "\n",
    "for key, value in person.items():\n",
    "    print(\"{}: {}\".format(key, value))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Tuples, Sets, Frozensets"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 20,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "<class 'tuple'> <class 'tuple'>\n"
     ]
    },
    {
     "ename": "TypeError",
     "evalue": "'tuple' object does not support item assignment",
     "output_type": "error",
     "traceback": [
      "\u001b[1;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[1;31mTypeError\u001b[0m                                 Traceback (most recent call last)",
      "\u001b[1;32m<ipython-input-20-95dd03038e47>\u001b[0m in \u001b[0;36m<module>\u001b[1;34m()\u001b[0m\n\u001b[0;32m      7\u001b[0m \u001b[0mprint\u001b[0m\u001b[1;33m(\u001b[0m \u001b[0mtype\u001b[0m\u001b[1;33m(\u001b[0m\u001b[0mt1\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m,\u001b[0m \u001b[0mtype\u001b[0m\u001b[1;33m(\u001b[0m\u001b[0mt2\u001b[0m\u001b[1;33m)\u001b[0m \u001b[1;33m)\u001b[0m     \u001b[1;31m# both are tuples\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0;32m      8\u001b[0m \u001b[1;33m\u001b[0m\u001b[0m\n\u001b[1;32m----> 9\u001b[1;33m \u001b[0mt1\u001b[0m\u001b[1;33m[\u001b[0m\u001b[1;36m0\u001b[0m\u001b[1;33m]\u001b[0m \u001b[1;33m=\u001b[0m \u001b[1;36m1\u001b[0m    \u001b[1;31m# will crash, tuples are immutable once declared\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[1;31mTypeError\u001b[0m: 'tuple' object does not support item assignment"
     ]
    }
   ],
   "source": [
    "# declaring a tuple\n",
    "\n",
    "t1 = (\"hello\", 2, \"hello\")    # with parens\n",
    "\n",
    "t2 = True, 1     # without parens\n",
    "\n",
    "print( type(t1), type(t2) )     # both are tuples\n",
    "\n",
    "t1[0] = 1    # will crash, tuples are immutable once declared"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 23,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "{2, 3, 5}\n"
     ]
    }
   ],
   "source": [
    "# declaring a set\n",
    "\n",
    "s1 = set( [1, 2, 3, 1] )    # uses the set keyword\n",
    "\n",
    "s2 = {4, 4, 5}    # uses curly brackets, like dictionary\n",
    "\n",
    "s1.add(5)     # using the add method to add new items to a set\n",
    "\n",
    "s1.remove(1)    # using the remove method to get rid of the value 1\n",
    "\n",
    "print(s1)     # notice when printed it removed the second \"1\" at the end"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 24,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "<class 'frozenset'>\n"
     ]
    }
   ],
   "source": [
    "# declaring a frozenset\n",
    "\n",
    "fset = frozenset([1, 2, 3, 4])\n",
    "\n",
    "print( type(fset) )"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "collapsed": true
   },
   "source": [
    "# Reading & Writing Files"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 31,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "this is a test\n"
     ]
    }
   ],
   "source": [
    "# opening/creating and writing to a text file\n",
    "\n",
    "f = open(\"test.txt\", 'w+')     # open file in writing and reading mode\n",
    "\n",
    "f.write('this is a test')\n",
    "\n",
    "f.close()\n",
    "\n",
    "# reading from a text file\n",
    "f = open('test.txt', 'r')\n",
    "\n",
    "data = f.read()\n",
    "\n",
    "f.close()\n",
    "\n",
    "print(data)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 32,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "# opening/creating and writing to a csv file\n",
    "import csv\n",
    "\n",
    "with open('test.csv', mode='w', newline='') as f:\n",
    "    writer = csv.writer(f, delimiter=',')\n",
    "    writer.writerow(['Name', 'City'])\n",
    "    writer.writerow(['Craig Lou', 'Taiwan'])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 33,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "['Name', 'City']\n",
      "['Craig Lou', 'Taiwan']\n"
     ]
    }
   ],
   "source": [
    "# reading from csv files\n",
    "\n",
    "with open('test.csv', mode='r') as f:\n",
    "    reader = csv.reader(f, delimiter=',')\n",
    "    \n",
    "    for row in reader:\n",
    "        print(row)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "collapsed": true
   },
   "source": [
    "# Friday project: Creating a User Database with CSV Files"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 34,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Thanks for using our software!\n"
     ]
    }
   ],
   "source": [
    "# import all necessary packages to be used\n",
    "import csv\n",
    "from IPython.display import clear_output\n",
    "\n",
    "# handle user registration and writing to csv\n",
    "def registerUser():\n",
    "    with open('users.csv', mode='a', newline='') as f:\n",
    "        writer = csv.writer(f, delimiter=',')\n",
    "        \n",
    "        print('To register, please enter your info:')\n",
    "        email = input('E-mail: ')\n",
    "        password = input('Password: ')\n",
    "        password2 = input('Re-type password: ')\n",
    "\n",
    "        clear_output()\n",
    "        \n",
    "        if password == password2:\n",
    "            writer.writerow([email, password])\n",
    "            print('You are now registered!')\n",
    "        else:\n",
    "            print('Something went wrong. Try again.')\n",
    "            \n",
    "# ask for user info and return true to login\n",
    "def loginUser():\n",
    "    print('To login, please enter your info:')\n",
    "    email = input('E-mail: ')\n",
    "    password = input('Password: ')\n",
    "    \n",
    "    clear_output()\n",
    "    \n",
    "    with open('users.csv', mode='r') as f:\n",
    "        reader = csv.reader(f, delimiter=',')\n",
    "        \n",
    "        for row in reader:\n",
    "            if row == [email, password]:\n",
    "                print('You are now logged in!')\n",
    "                return True\n",
    "    \n",
    "    print('Something went wrong, try again.')\n",
    "    return False\n",
    "            \n",
    "# variables for main loop\n",
    "active = True\n",
    "logged_in = False\n",
    "\n",
    "# main loop\n",
    "while active:\n",
    "    if logged_in:\n",
    "        print('1. Logout\\n2. Quit')\n",
    "    else:\n",
    "        print('1. Login\\n2. Register\\n3. Quit')\n",
    "    \n",
    "    choice = input('What would you like to do? ').lower()\n",
    "    \n",
    "    clear_output()\n",
    "    \n",
    "    if choice == 'register' and logged_in == False:\n",
    "        registerUser()\n",
    "    elif choice == 'login' and logged_in == False:\n",
    "        logged_in = loginUser()\n",
    "    elif choice == 'quit':\n",
    "        active = False\n",
    "        print('Thanks for using our software!')\n",
    "    elif choice == 'logout' and logged_in == True:\n",
    "        logged_in = False\n",
    "        print('You are now logged out.')\n",
    "    else:\n",
    "        print('Sorry, please try again!')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Monday Exercises - Answers"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "<p>\n",
    "1. <b>User Input:</b> Ask the user for their name and age, then create a dictionary with those key-value pairs. Output the dictionary once created.\n",
    "</p>"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "What is your name? Connor\n",
      "What is your age? 27\n",
      "{'name': 'Connor', 'age': '27'}\n"
     ]
    }
   ],
   "source": [
    "name = input('What is your name? ')\n",
    "age = input('What is your age? ')\n",
    "\n",
    "person = { 'name' : name, 'age' : age }\n",
    "\n",
    "print(person)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "<p>\n",
    "2. <b>Accessing Ingredients:</b> Output all the ingredients from the list below within the 'ingredients' key using a for loop:\n",
    "</p>\n",
    "\n",
    "<p>\n",
    ">>> pizza = { <br>\n",
    ">>> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'ingredients' : ['cheese', 'sausage', 'peppers'] <br>\n",
    ">>> }\n",
    "</p>"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "cheese\n",
      "sausage\n",
      "peppers\n"
     ]
    }
   ],
   "source": [
    "pizza = {\n",
    "    'ingredients' : ['cheese', 'sausage', 'peppers']\n",
    "}\n",
    "\n",
    "for topping in pizza['ingredients']:\n",
    "    print(topping)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Tuesday Exercises - Answers"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "<p>\n",
    "1. <b>User Input:</b> Declare an empty dictionary. Ask the user for their name, address, and number. Add that information to the dictionary and iterate over it to show the user.\n",
    "</p>"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 19,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "What is your name? John Smith\n",
      "What is your address? 5 Main Street, Boston, MA\n",
      "What is your number? 800-828-7300\n",
      "name: John Smith\n",
      "address: 5 Main Street, Boston, MA\n",
      "number: 800-828-7300\n"
     ]
    }
   ],
   "source": [
    "info = {}\n",
    "\n",
    "name = input('What is your name? ')\n",
    "address = input('What is your address? ')\n",
    "number = input('What is your number? ')\n",
    "\n",
    "info['name'] = name\n",
    "info['address'] = address\n",
    "info['number'] = number\n",
    "\n",
    "for k, v in info.items():\n",
    "    print(\"{}: {}\".format(k, v))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "<p>\n",
    "2. <b>Problem Solving:</b> What is wrong with the following code:\n",
    "</p>\n",
    "\n",
    "<p>\n",
    ">>> person = { 'name', 'John Smith' } <br>\n",
    ">>> print(person['name'])\n",
    "</p>"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "# the name key and John Smith value should be separated by a colon, not comma"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Wednesday Exercises - Answers"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "<p>\n",
    "1. <b>User Input:</b> Ask the user to input as many bank account numbers as they'd like and store them within a list initially. Once the user is done entering information, convert the list to a frozenset and print it out.\n",
    "</p>"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 28,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Enter an account number or quit: 1\n",
      "Enter an account number or quit: quit\n",
      "Account Number: 1\n"
     ]
    }
   ],
   "source": [
    "accounts = []\n",
    "done = False\n",
    "\n",
    "while not done:\n",
    "    ans = input('Enter an account number or quit: ').lower()\n",
    "    \n",
    "    if ans == 'quit':\n",
    "        done = True\n",
    "        \n",
    "        accounts = frozenset(accounts)\n",
    "        for acc in accounts:\n",
    "            print(\"Account Number: {}\".format(acc))\n",
    "            \n",
    "    else:\n",
    "        accounts.append(ans)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "<p>\n",
    "2. <b>Conversion:</b> Convert the list below into a set of unique values. Print it out after to check there are no duplicates.\n",
    "</p>\n",
    "\n",
    "<p>\n",
    ">>> nums = [3, 4, 3, 7, 10]\n",
    "</p>"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 29,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "{10, 3, 4, 7}\n"
     ]
    }
   ],
   "source": [
    "nums = [3, 4, 3, 7, 10]\n",
    "\n",
    "nums = set(nums)\n",
    "\n",
    "print(nums)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Thursday Exercises - Answers"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "<p>\n",
    "1. <b>User Input:</b> Ask a user for their favorite number and save it to a text file.\n",
    "</p>"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 35,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "What is your favorite number? 9\n"
     ]
    }
   ],
   "source": [
    "ans = input(\"What is your favorite number? \")\n",
    "\n",
    "f = open(\"numbers.txt\", 'w+')     # open file in writing and reading mode\n",
    "\n",
    "f.write('favorite number is {}'.format(ans))\n",
    "\n",
    "f.close()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "<p>\n",
    "2. <b>Data Dumping:</b> Using the dictionary of data below, save the information to a csv file with the keys as the headers and the values as the rows of data.\n",
    "</p>\n",
    "\n",
    "<p>\n",
    ">>> data = { <br>\n",
    ">>> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'name' : [\"Dave\", \"Dennis\", \"Peter\", \"Jess\"], <br>\n",
    ">>> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'language' : ['Python', 'C', 'Java', 'Python'] <br>\n",
    ">>> }\n",
    "</p>"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 36,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "data = {\n",
    "    'name' : ['Dave', 'Dennis', 'Peter', \"Jess\"],\n",
    "    'language' : ['Python', 'C', 'Java', 'Python']\n",
    "}\n",
    "\n",
    "import csv\n",
    "\n",
    "with open('data.csv', mode='w', newline='') as f:\n",
    "    writer = csv.writer(f, delimiter=',')\n",
    "    writer.writerow(data.keys())\n",
    "    \n",
    "    for i in range(len(data['name'])):\n",
    "        writer.writerow([data['name'][i], data['language'][i]])"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# End of Week Exercises - Answers"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "<p>\n",
    "1. <b>Changing Passwords:</b> Add a function called \"changePassword\" to the project from Friday that will allow users to change their password when logged in.\n",
    "</p>"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Thanks for using our software!\n"
     ]
    }
   ],
   "source": [
    "# import all necessary packages to be used\n",
    "import csv\n",
    "from IPython.display import clear_output\n",
    "\n",
    "# handle user changing password\n",
    "def changePassword():\n",
    "    ''' \n",
    "        This function must confirm email and pass, then read data and save to local list\n",
    "        because you cannot change a single value, you must save all data, then overwrite\n",
    "        the entire file all together.\n",
    "    '''\n",
    "    \n",
    "    email = input('Please confirm your e-mail: ')\n",
    "    password = input('Please confirm your current password: ')\n",
    "    \n",
    "    emails = []\n",
    "    passwords = []\n",
    "    found = False\n",
    "\n",
    "    with open('users.csv', mode='r') as f:\n",
    "        reader = csv.reader(f, delimiter=',')\n",
    "        \n",
    "        for row in reader:\n",
    "            if row == [email, password]:\n",
    "                found = True\n",
    "            elif row:\n",
    "                emails.append(row[0])\n",
    "                passwords.append(row[1])\n",
    "    \n",
    "    if found:\n",
    "        new_pass = input('What would you like to change your password to? ')\n",
    "        \n",
    "        emails.append(email)\n",
    "        passwords.append(new_pass)\n",
    "        \n",
    "        with open('users.csv', mode='w') as f:\n",
    "            writer = csv.writer(f, delimiter=',')\n",
    "            \n",
    "            for i in range(len(emails)):\n",
    "                writer.writerow([emails[i], passwords[i]])\n",
    "    else:\n",
    "        print('Sorry those credentials were incorrect.')\n",
    "\n",
    "# handle user registration and writing to csv\n",
    "def registerUser():\n",
    "    with open('users.csv', mode='a', newline='') as f:\n",
    "        writer = csv.writer(f, delimiter=',')\n",
    "        \n",
    "        print('To register, please enter your info:')\n",
    "        email = input('E-mail: ')\n",
    "        password = input('Password: ')\n",
    "        password2 = input('Re-type password: ')\n",
    "\n",
    "        clear_output()\n",
    "        \n",
    "        if password == password2:\n",
    "            writer.writerow([email, password])\n",
    "            print('You are now registered!')\n",
    "        else:\n",
    "            print('Something went wrong. Try again.')\n",
    "            \n",
    "# ask for user info and return true to login\n",
    "def loginUser():\n",
    "    print('To login, please enter your info:')\n",
    "    email = input('E-mail: ')\n",
    "    password = input('Password: ')\n",
    "    \n",
    "    clear_output()\n",
    "    \n",
    "    with open('users.csv', mode='r') as f:\n",
    "        reader = csv.reader(f, delimiter=',')\n",
    "        \n",
    "        for row in reader:\n",
    "            if row == [email, password]:\n",
    "                print('You are now logged in!')\n",
    "                return True\n",
    "    \n",
    "    print('Something went wrong, try again.')\n",
    "    return False\n",
    "            \n",
    "# variables for main loop\n",
    "active = True\n",
    "logged_in = False\n",
    "\n",
    "# main loop\n",
    "while active:\n",
    "    if logged_in:\n",
    "        print('1. Logout\\n2. Change Password\\n3. Quit')\n",
    "    else:\n",
    "        print('1. Login\\n2. Register\\n3. Quit')\n",
    "    \n",
    "    choice = input('What would you like to do? ').lower()\n",
    "    \n",
    "    clear_output()\n",
    "    \n",
    "    if choice == 'register' and logged_in == False:\n",
    "        registerUser()\n",
    "    elif choice == 'login' and logged_in == False:\n",
    "        logged_in = loginUser()\n",
    "    elif choice == 'quit':\n",
    "        active = False\n",
    "        print('Thanks for using our software!')\n",
    "    elif choice == 'logout' and logged_in == True:\n",
    "        logged_in = False\n",
    "        print('You are now logged out.')\n",
    "    elif choice == 'change password' and logged_in == True:\n",
    "        changePassword()\n",
    "    else:\n",
    "        print('Sorry, please try again!')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "<p>\n",
    "2. <b>Favorite Food:</b> Write a new program that will ask users what their favorite food is. Save the answers to a csv file called \"favorite_food.csv\". After answering, display a table of tallied results. Example of table:\n",
    "</p>\n",
    "\n",
    "<p>\n",
    "<b>Favorite Food?</b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<b># of Votes</b> <br>\n",
    "<b>Turkey</b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<b>5</b><br>\n",
    "<b>Salad</b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<b>3</b>\n",
    "</p>"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Here are the results so far...\n",
      "bacon: 4\n",
      "bread: 2\n"
     ]
    }
   ],
   "source": [
    "def saveFood():\n",
    "    ans = input('What is your favorite food? ')\n",
    "    \n",
    "    with open('favorite_food.csv', mode='a', newline='') as f:\n",
    "        writer = csv.writer(f, delimiter=',')\n",
    "        \n",
    "        writer.writerow([ans])\n",
    "    \n",
    "    print('Food added!')\n",
    "    \n",
    "def countFood():\n",
    "    food_count = {}\n",
    "    \n",
    "    with open('favorite_food.csv', mode='r') as f:\n",
    "        reader = csv.reader(f, delimiter=',')\n",
    "        \n",
    "        for row in reader:\n",
    "            if row[0].lower() in food_count:\n",
    "                food_count[row[0].lower()] += 1\n",
    "            else:\n",
    "                food_count[row[0].lower()] = 1\n",
    "                \n",
    "    return food_count\n",
    "\n",
    "def main():\n",
    "    while input('Would you like to add more? ').lower() != 'no':\n",
    "        saveFood()\n",
    "        \n",
    "    clear_output()\n",
    "    \n",
    "    print('Here are the results so far...')\n",
    "    \n",
    "    food_count = countFood()\n",
    "    \n",
    "    for k, v in food_count.items():\n",
    "        print(\"{}: {}\".format(k, v))\n",
    "        \n",
    "main()"
   ]
  }
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