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  <title>Week 6 - Dictionaries</title>

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      <section>
        <br>
        <h2>Python 101</h2>
        <h3>Week 6:<br>Dictionaries</h3>
        <p>
          <small>Expedia Code Academy</small>
          <br>
          <img src="static/img/code_academy_logo.png" border="0px">
        </p>
      </section>

      <section>
        <h3>Dictionaries</h3>
        <p>
          I have a dictionary, and I want to look up the meaning of the word <i>hotel</i>.<br>
        </p>
        <p class="fragment">
          You can describe this data as having a key (hotel) and a value (the definition). This is a data structure in
          Python!<br>
        </p>
        <p class="fragment">
          Here's a dictionary representing people (keys) and their favourite animals (values):
          <img src="static/img/dict.png">
        </p>
      </section>

      <section>
        <h3>Dictionaries</h3>
        <p>
          So far we have seen lists, where we grab elements using their numbered position, or index.<br><br>

          Dictionaries are similar to lists, except you access the elements using <b>unordered keys</b>

          <div class="fragment">
            <pre><code class="python" data-trim>
                eng_dict = {} # let's create an English dictionary

                # then add words to it
                eng_dict['hotel'] = 'An establishment providing accommodation.'
                eng_dict['flight'] = 'The process of flying through the air.'

                print(eng_dict)
              </code></pre>
          </div>
        </p>
      </section>

      <section>
        <h3>Dictionaries</h3>
        <p>
          You can also create a dictionary with data in it:
          <div>
            <pre><code class="python" data-trim>
                # We can define a dictionary in one line too
                eng_dict = {
                  'hotel': 'An establishment providing accommodation',
                  'flight': 'The process of flying through the air'
                }

                print(eng_dict['hotel']) # to print a value from the dictionary
              </code></pre>
          </div>
        </p>
        <p class="fragment">
        (⭐️) 6a. Create a dictionary of the class' favourite animals
        </p>
      </section>

      <section>
        <h3>Dictionary operations</h3>

        We can also modify existing dictionaries - the syntax is the same as adding new values.
        <p>
          <div>
            <pre><code class="python" data-trim>
                eng_dict = {
                  'hotel': 'An establishment providing accommodation',
                  'flight': 'The process of flying through the air'
                }

                eng_dict['hotel'] = 'An establishment providing accommodation, buy now at Hotels.com!'

                # We can find the number of key-value pairs in the dictionary
                len(inventory) # just like for lists
              </code></pre>
          </div>
        </p>
        <p class="fragment">
          (⭐️⭐️) 6b. Use <span id="code">input()</span> to add someone's name and their favourite animal dynamically.
        </p>
      </section>

      <section>
        <h3>Dictionary exercise</h3>

        (⭐️⭐️) 6c. Let's access data in a dictionary!
        <pre><code class="python" data-trim>
            hotel = {
                'name': 'Corinthia Hotel',
                'amenities': ['Indoor pool', 'Fitness centre', 'Spa'],
                'top spots': [
                    {'name': 'Trafalgar Square', 'proximity': 300},
                    {'name': 'London Eye', 'proximity': 450},
                    {'name': 'Buckingham Palace', 'proximity': 1200}
                 ]
            }
          </code></pre>

        <small>
          How can you:<br>
          <ul>
            <li>Access the hotel name?</li>
            <li>Find out how many amenities it has?</li>
            <li>Find out the names of the top spots near it?</li>
            <li>Find out all the top spots within 500 metres reach?</li>
          </ul>
        </small>
      </section>

      <section>
        <h3>Appendix: Dictionary methods</h3>

        We can get lists of all keys or all values.
        <p>
          <div class="fragment">
            <pre><code class="python" data-trim>
                inventory = {'apples': 320, 'pears': 228, 'bananas': 420}

                print(inventory.keys())
                # will print ['apples', 'pears', 'bananas']
                print(inventory.values())
                # will print [320, 228, 420]
              </code></pre>
          </div>
        </p>

        <span class="fragment">
          Or we can check if a dictionary contains a given key, just like in lists. <br>
        </span>

        <p>
          <div class="fragment">
            <pre><code class="python" data-trim>
                inventory = {'apples': 320, 'pears': 228, 'bananas': 420}

                'apples' in inventory # will return True
                'oranges' in inventory # will return False
              </code></pre>
          </div>
        </p>

      </section>

      <section>
        <h3>Appendix: Dictionary exercises</h3>
        <pre><code class="python" data-trim>
              inventory = {'apples': 3, 'pears': 2, 'bananas': 0}
          </code></pre>
        <small>
          <ul>
            <li>
              (⭐️⭐️) 6d. Let's go shopping! For this exercise use the following dictionary:
            </li>
            <ul>
              <li>
                The program should handle the following scenario:
              </li>
              <li>
                A shopper would like to buy 1 item. Take user input of what that item is.
                <br>
                Assume that the user will type 'apples', 'pears' or 'bananas'!
              </li>
              <li>
                Update the inventory to reflect that purchase - i.e. if someone buys apples, their value would go from 3
                to 2.
              </li>
            </ul>
            </li>
            <li>
              (⭐️⭐️⭐️) 6e. Add the following functionality to your shopping program:
              <ul>
                <li>
                  i. If that item doesn't exist, let the user know.
                </li>
                <li>
                  ii. If that item is sold out, let the user know.
                </li>
                <li>
                  iii. (🔥) Also ask the user for how many items they'd like to buy. Hint: you'll need
                  <pre><code class="python" data-trim>
                      how_many = input('How many items would you like to buy?')
                      how_many = int(how_many)  # convert string to number (int = integer)
                    </code></pre>
                </li>
              </ul>
            </li>
            <br>
          </ul>
        </small>
      </section>

      <section>
        <h3>Appendix: Dictionary creation exercises</h3>
        <ul>
          <li>(⭐️️️⭐️️️⭐️) 6f. Write a program that tracks the count of the letters from a string.
            <br><br>
            Given the string <span id="code">'expedia'</span> the expected output is:
            <br>
            <pre><code class="python" data-trim>
                      {'e': 2, 'x': 1, 'p': 1, 'd': 1, 'i': 1, 'a': 1}
                </code></pre>
          </li>
          <br>
        </ul>
      </section>

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