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        <title>Intro to Python ~ Girl Develop It</title>

        <meta name="description" content="This is the official Girl Develop It Core Intro to Python course. The course is meant to be taught in four two-hour sessions. Each of the slides and practice files are customizable according to the needs of a given class or audience.">
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            <!-- Any section element inside of this container is displayed as a slide -->
            <div class="slides">
              <!-- Opening slide -->
                <section>
                  <img src = "images/gdi_logo_badge.png">
                  <h3>Intro to Python</h3>
                  <h4>Class 1</h4>
                </section>

                <!-- Welcome-->
                <section>
                  <h3>Welcome!</h3>
                  <div class = "left-align">
                  <p>Girl Develop It is here to provide affordable and accessible programs to learn software through mentorship and hands-on instruction.</p>
                  <p class ="green">Some "rules"</p>
                  <ul>
                    <li>We are here for you!</li>
                    <li>Every question is important</li>
                    <li>Help each other</li>
                    <li>Have fun</li>
                  </ul>
                  </div>
                </section>

                <section>
                  <h3>What we will cover today</h3>
                  <ul>
                    <li class ="fragment">Why Python?</li>
                    <li class ="fragment">What is programming?</li>
                    <li class ="fragment">Variables and arithmetic</li>
                    <li class ="fragment">Statements and Error Messages</li>
                    <li class ="fragment">Development Environment Setup</li>
                  </ul>
                </section>

                <!-- Block 1: 25 minutes -->
                <section>
                  <h3>Why Python?</h3>
                  <ul>
                    <li class ="fragment">Suitable for beginners, yet used by professionals</li>
                    <li class ="fragment">Readable, maintainable code</li>
                    <li class ="fragment">Rapid rate of development</li>
                    <li class ="fragment">Few "magical" side-effects</li>
                    <li class ="fragment">Variety of applications</li>
                  </ul>
                </section>

                <section>
                  <h3>What is Python used for?</h3>
                  <ul>
                    <li class ="fragment">System Administration (Fabric, Salt, Ansible)</li>
                    <li class ="fragment">3D animation and image editing (Maya, Blender, Gimp)</li>
                    <li class ="fragment">Scientific computing (numpy, scipy)</li>
                    <li class ="fragment">Web development (Django, Flask)</li>
                    <li class ="fragment">Game Development (Civilization 4, EVE Online)</li>
                  </ul>
                </section>

                <section>
                  <h3>Who is using Python?</h3>
                  <ul>
                    <li>Disney</li>
                    <li>Dropbox</li>
                    <li>Canonical and Red Hat</li>
                    <li>Google</li>
                    <li>NASA</li>
                  </ul>
                </section>

                <section>
                    <h3>What is programming?</h3>
                    <ul>
                        <li class="fragment">Teaching the computer to do a task</li>
                        <li class="fragment">A program is made of one or more files of code, each of which solve part of the overall task</li>
                        <li class="fragment">Programming code is human readable but also needs a form that the computer can run directly. This form is not human readable.</li>
                        <li class="fragment">To create the form of code the computer can use, we use the Python <a href="http://en.wikipedia.org/wiki/Interpreter_(computing)">interpreter</a>. Other languages use other interpreters or a <a href="http://en.wikipedia.org/wiki/Compiler">compiler</a></li>
                        <li class="fragment">Don't focus on what's "under the hood" for now. We will "drive the car" first</li>
                        <li class="fragment">In other words, there are many layers to the onion. We start at one layer and slowly move toward layers that are beneath or above us</li>
                    </ul>
                </section>

                <section>
                    <h3>Command line, Python Shell, Text Editors</h3>
                    <table>
                        <tr>
                            <td><strong>Terminal</strong></td>
                            <td>A program that has a command line interface and issues commands to the operating system.</td>
                        </tr>
                        <tr>
                            <td><strong>Python Shell</strong></td>
                            <td>A command line program that runs inside of the terminal, takes Python code as input, interprets it, and prints out any results.</td>
                        </tr>
                        <tr>
                            <td><strong>Text Editor</strong></td>
                            <td>A program that opens text files and allows the user to edit and save them. (Different than a word processor).</td>
                        </tr>
                    </table>
                </section>

                <section>
                    <h3>Example Text Editors</h3>
                    <table>
                        <tr>
                            <td><strong>Linux</strong></td>
                            <td>Gedit, Jedit, Kate</td>
                        </tr>
                        <tr>
                            <td><strong>MacOSX</strong></td>
                            <td>TextMate, TextWrangler</td>
                        </tr>
                        <tr>
                            <td><strong>Windows</strong></td>
                            <td>Notepad++</td>
                        </tr>
                        <tr>
                            <td><strong>All</strong></td>
                            <td>Sublime Text, Vim, Emacs</td>
                        </tr>
                    </table>
                </section>

                <!-- Let's develop it: 10 minutes-->
                <section>
                    <h3>Let's Develop It</h3>
                    <p>Let's setup our computer for Python programming</p>
                    <ul>
                        <li>
                            Let's install a text editor -
                            <a href="http://www.sublimetext.com/2">Install Sublime Text 2</a>
                        </li>
                        <li>
                            <a href="http://www.python.org/download/">Install Python</a>
                            (This step is for Windows users only. GNU/Linux and MacOSX come with Python installed)
                        </li>
                        <li>
                            (Windows only): After installing Python, open the "powershell" program and type:
                            <pre>[Environment]::SetEnvironmentVariable("Path", "$env:Path;C:\Python27", "User")</pre>
                        </li>
                        <li>
                            Locate and run the terminal program. Type 'python' and hit enter.
                        </li>
                        <li>
                            More setup instructions are available:
                            <a href="http://learnpythonthehardway.org/book/ex0.html">here</a>
                            (You can, but don't have to install the other text editors recommended in this guide)
                        </li>
                    </ul>
                </section>
                <!-- Block 2: 30 minutes -->
                <section>
                    <h3>Working in the Python Shell</h3>
                    <p>Open up your terminal and type 'python'</p>
                    <p class="fragment">Follow along with the examples in the slides. Type them in!</p>
                    <p class="fragment">Feel free to explore as well. You will not accidentally break things</p>
                </section>

                <section>
                    <h3>Variables and Arithmetic</h3>
                    <pre><code contenteditable class="python">
3 + 4
2 * 4
6 - 2
4 / 2
                    </code></pre>
                    <pre><code contenteditable class="python">
a = 2
b = 3
print(a + b)
c = a + b
print(c * 2)
                    </code></pre>
                    <pre><code contenteditable class="python">
a = 0
a = a + .5
print(a)
                    </code></pre>
                </section>

                <section>
                    <h3>Strings</h3>
                    <pre><code contenteditable class="python">
a = 'Hello '
b = 'World'
c = a + b
print(c)
                    </code></pre>
                    <pre><code contenteditable class="python">
a = "Spam "
b = a * 4
print(b)
                    </code></pre>
                    <pre><code contenteditable class="python">
a = 'spam '
b = 'eggs'
c = a * 4 + b
print(c)
                    </code></pre>
                </section>

                <section>
                    <h3>Data types</h3>
                    <ul>
                        <li>Variables are names of objects</li>
                        <li>Among other things, variables are used to represent something that can't be known until the program is run</li>
                        <li>Objects always have a "type"</li>
                        <li>The type of an object helps define what it can do</li>
                        <li>The type can be found using: `type()`</li>
                        <li>type() is a <strong>function</strong>. We call it by using parenthesis and pass it an object by placing the object inside the parenthesis</li>
                    </ul>
                    <pre><code contenteditable class="python">
a = 4
print(type(a))
print(type(4))

print(type(3.14))

b = 'spam, again'
print(type(b))
print(type("But I don't like spam"))
                    </code></pre>
                </section>

                    <section>
                        <h3>Data types - continued ...</h3>
                        <ul>
                            <li>Objects can be used with a set of <strong>operators</strong></li>
                            <li>An int or float can be used with any of: +, -, *, /</li>
                            <li>A string can be used with any of: +, *</li>
                            <li>What happens if we try to use division or subtraction with a string?</li>
                        </ul>
                    <pre><code contenteditable class="python">
print("Spam" - "am")
a = 'Spam and eggs'
print(a / 'hashbrowns')
print(a / 6)
                    </code></pre>
                    </section>

                    <section>
                        <h3>Errors</h3>
                        <ul>
                            <li class="fragment">There are different kinds of errors that can occur. We've seen a few of these so far</li>
                            <li class="fragment">A runtime error results in an <strong>Exception</strong> of which there are several types. Each type gives us some information about the nature of the error and how to correct it</li>
                            <li class="fragment">One type of exception is a <strong>SyntaxError</strong>. This results when our code can not be evaluated because it is incorrect at a syntactic level. In other words, we are not following the "rules" of the language.</li>
                            <li class="fragment">Some other examples are the <strong>TypeError</strong> and <strong>NameError</strong> exceptions.</li>
                        </ul>
                    </section>

                    <section>
                    <h3>Errors - continued ...</h3>
                    <pre><code contenteditable class="python">
# SyntaxError - Doesn't conform to the rules of Python. This statement isn't meaningful to the computer
4spam)eggs(garbage) + 10

# NameError - Using a name that hasn't been defined yet
a = 5
print(b)
b = 10

# TypeError - Using an object in a way that its type does not support
'string1' - 'string2'
                    </code></pre>
                    <p class="fragment">There are also <strong>semantic</strong> errors. These are harder to catch because the computer can't catch them for us.</p>
                </section>

                <!-- Let's develop it: 10 minutes -->
                <section>
                    <h3>Let's Develop It</h3>
                    <p>We'll practice what we've learned in the shell</p>
                    <p>Review the slides on your computer and practice entering any commands you didn't fully understand before</p>
                    <p>Ask the teacher or a TA for any help</p>
                </section>

                <!-- Block 3 30 minutes -->

                <section>
                    <h3>Using the Terminal</h3>
                    <p>Try each of the following commands in turn:</p>
                    <table>
                        <tr>
                            <th><strong>Command</strong></th>
                            <th><strong>Short for</strong></th>
                            <th><strong>Description</strong></th>
                        </tr>
                        <tr>
                            <td>pwd</td>
                            <td>Print working directory</td>
                            <td>Displays what folder you are in.</td>
                        </tr>
                        <tr>
                            <td>ls</td>
                            <td>List</td>
                            <td>Lists the files and folders in the current folder</td>
                        </tr>
                        <tr>
                            <td>cd</td>
                            <td>Change directory</td>
                            <td>Change to another folder. Takes the folder name as an argument. 'cd ..' goes up a directory</td>
                        </tr>
                        <tr>
                            <td>cat</td>
                            <td>Concatenate</td>
                            <td>Prints the contents of a file. Takes a filename as an argument</td>
                        </tr>
                    </table>
                </section>

                <section>
                    <h3>Creating a folder</h3>
                    <p>We need a folder to save our work in.</p>
                    <p class="fragment">The -&gt;'s below indicate the expected output of the previous command.</p>
                    <pre><code contenteditable class="fragment bash">
pwd
-> /home/username
mkdir Projects
cd Projects
mkdir gdi-intro-python
cd gdi-intro-python
pwd
-> /home/username/Projects/gdi-intro-python
                    </code></pre>
                    <p class="fragment">Now that the folders are made, we only have to use 'cd Projects/gdi-intro-python' in the future.</p>
                </section>

                <section>
                    <h3>The Text Editor</h3>
                    <p>Open sublime text.</p>
                    <ul>
                        <li class="fragment">Click file, open folder. Navigate to the gdi-intro-python folder we created and click "open"</li>
                        <li class="fragment">In the text editor, enter the following:
                    <pre><code contenteditable class="fragment python">
print('I am a Python program')
                    </code></pre>
                        </li>
                        <li class="fragment">Click file, save as. Type 'class1.py' and click ok.</li>
                        <li class="fragment">Open a terminal and navigate to the gdi-intro-python folder (if not left open from before)</li>
                        <li class="fragment">Type 'python class1.py'</li>
                        <li class="fragment">You should see the terminal print "I am a Python program"</li>
                    </ul>
                </section>

                <section>
                    <h3>User Input</h3>
                    <p>To obtain user input, use 'raw_input()' or in python3 use 'input()'</p>
                    <p class="fragment">Change the class1.py text to the following and run it again</p>
                    <pre><code contenteditable class="fragment python">
input_value = raw_input("Enter a radius:")  # input("enter a radius:") in python3
radius = float(input_value)
area = 3.14159 * radius ** 2
print("The area of a circle with radius " + input_value + " is:")
print(area)
                    </code></pre>
                    <p class="fragment">N.B. - The user's input is a string so we use float() to make it a number</p>
                </section>

                <!-- Let's develop it: 15 minutes -->
                <section>
                    <h3>Let's Develop It</h3>
                    <p>Write your own program that uses raw_input/input and does something else with the value</p>
                    <p>You can use float() to treat the input as a number if you need a number, or use the input directly as a string</p>
                </section>

                <section>
                    <h3>Questions?</h3>
                </section>
                <section></section>
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