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<header>
<h1>Intro to Python</h1>
</header>
<ul>
<li><a href="#Data_Types" class="nav-link">Data Types</a></li>
<li><a href="#Print_a_Message" class="nav-link">Print a Message</a></li>
<li><a href="#Variables" class="nav-link">Variables</a></li>
<li><a href="#Input" class="nav-link">Input</a></li>
<li><a href="#Lists" class="nav-link">Lists</a></li>
<li><a href="#Tuples" class="nav-link">Tuples</a></li>
<li><a href="#Dictionaries" class="nav-link">Dictionaries</a></li>
<li><a href="#Conditions" class="nav-link">Conditions</a></li>
<li><a href="#For_Loops" class="nav-link">For Loops</a></li>
<li><a href="#While_Loops" class="nav-link">While Loops</a></li>
<li><a href="#Functions" class="nav-link">Functions</a></li>
<li><a href="#Classes" class="nav-link">Classes</a></li>
<li><a href="#References" class="nav-link">References</a></li>
</ul>
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<main id="main-doc">
<section class="main-section" id="Data_Types">
<header>
<h1>Data Types</h1>
</header>
<table>
<thead>
<th>Category</th>
<th>Types</th>
</thead>
<tbody>
<tr>
<td>Text</td>
<td><code>str</code></td>
</tr>
<tr>
<td>Numeric</td>
<td><code>int</code>, <code>float</code>, <code>complex</code></td>
</tr>
<tr>
<td>Sequence</td>
<td><code>list</code>, <code>tuple</code>, <code>range</code></td>
</tr>
<tr>
<td>Mapping</td>
<td><code>dict</code></td>
</tr>
<tr>
<td>Set</td>
<td><code>set</code>, <code>frozenset</code></td>
</tr>
<tr>
<td>Boolean</td>
<td><code>bool</code></td>
</tr>
<tr>
<td>Binary</td>
<td><code>bytes</code>, <code>bytearray</code>, <code>memoryview</code></td>
</tr>
</tbody>
</table>
</section>
<section class="main-section" id="Print_a_Message">
<header>
<h1>Print a Message</h1>
</header>
<p>You can print a message onto the screen with the <code>print()</code> function</p>
<p>For example, to print a <em>string</em> value:</p>
<pre>print("Hello World!")</pre>
<p><samp>Hello World!</samp></p>
<p>You can print numbers and operations:</p>
<pre>print(5 + 2)</pre>
<p><samp>7</samp></p>
<pre>print(5 * 2)</pre>
<p><samp>10</samp></p>
<pre>print(3 ** 3)</pre>
<p><samp>27</samp></p>
<p>You can print many values at once:</p>
<pre>print("Hi", 3 + 1)</pre>
<p><samp>Hi 4</samp></p>
</section>
<section class="main-section" id="Variables">
<header>
<h1>Variables</h1>
</header>
<p>When you are programming, there are many situations in which you have to use a value many times or save it. Instead of <a href="https://en.wikipedia.org/wiki/Hard_coding" target="_blank">hard-coding</a> that value you can use variables. Let's see an example:</p>
<pre>x = "Hello" # This is how a variable is declared</pre>
<p>You can print variables and operate with them:</p>
<pre>x = 5<br>print(x)</pre>
<p><samp>5</samp></p>
<pre>print(x - 3)</pre>
<p><samp>2</samp></p>
<pre>x = 42<br>y = 50<br>print(x + y)</pre>
<p><samp>92</samp></p>
<pre>x = 15<br>y = 2 * x<br>print(y)</pre>
<p><samp>30</samp></p>
</div>
</section>
<section class="main-section" id="Input">
<header>
<h1>Input</h1>
</header>
<p>With the <code>input()</code> function, the user can enter a value and save it in a variable. Let's see an example:</p>
<pre>my_example = input()<br>print(my_example)</pre>
<p><kbd>Hello!</kbd></p>
<p><samp>Hello!</samp></p>
<p>But when a number is entered and you want to operate with it, the operations will not work because the <code>input()</code> function returns <em>string</em> values. To solve this, before writing <code>input()</code>, specify the data type:</p>
<pre>float(input()) # For example</pre>
<p>Also, you can write a message to specify to the user what to enter. For example:</p>
<pre>name = input("Enter your name: ")</pre>
<p><kbd>Enter your name: </kbd></p>
</section>
<section class="main-section" id="Lists">
<header>
<h1>Lists</h1>
</header>
<p>Lists are ordered and changeable collections. They are written with square brackets. Let's see an example:</p>
<pre>my_list = ["Literature" , "Music" , "Films" , "TV" , "Videogames"]</pre>
<p>You can access the items by referring to the index number <u>(the first position is 0)</u>:</p>
<pre>print(my_list[1])</pre>
<p><samp>Music</samp></p>
<p>When you write a negative index like <code>-1</code>, you will get the last item, with <code>-2</code>, the second last item...</p>
<pre>print(my_list[-1])</pre>
<p><samp>Videogames</samp></p>
<p>You can use a range of indexes:</p>
<pre>print(my_list[2:4])</pre>
<p><samp>['Films', 'TV']</samp></p>
<p>Lists are changeable and there are many methods. Let's see some of them:</p>
<p><code>append()</code> Adds an element at the end of the list:</p>
<pre>my_list.append("Radio")<br>print(my_list)</pre>
<p><samp>['Literature', 'Music', 'Films', 'TV', 'Videogames', 'Radio']</samp></p>
<p><code>pop()</code> Removes the element at the specified position:</p>
<pre>my_list = ["Literature" , "Music" , "Films" , "TV" , "Videogames"]<br>my_list.pop(1)<br>print(my_list)</pre>
<p><samp>['Literature', 'Films', 'TV', 'Videogames']</samp></p>
<p>You can check more list methods at:</p>
<ul>
<li><a href="https://docs.python.org/3/tutorial/datastructures.html#more-on-lists" target="_blank">Python Docs</a></li>
<li><a href="https://www.w3schools.com/python/python_ref_list.asp" target="_blank">W3Schools</a></li>
</ul>
</section>
<section class="main-section" id="Tuples">
<header>
<h1>Tuples</h1>
</header>
<p>Tuples, like lists, are collections that are ordered but <strong>UNCHANGEABLE</strong>. Tuples are written with round brackets:</p>
<pre>my_tuple = ("Literature" , "Music" , "Films" , "TV" , "Videogames")</pre>
<p>The only way to modify a tuple is by transforming it into a list and then into a tuple. Let's see an example:</p>
<pre>my_tuple = ("Literature" , "Music" , "Films" , "TV" , "Videogames")<br>my_tuple = list(my_tuple)<br>my_tuple.pop()<br>my_tuple = tuple(my_tuple)<br>print(my_tuple)</pre>
<p><samp>('Literature', 'Music', 'Films', 'TV')</samp></p>
</section>
<section class="main-section" id="Dictionaries">
<header>
<h1>Dictionaries</h1>
</header>
<p>Dictionaries are unordered, changeable and indexed. They have keys and values. Let's see an example:</p>
<pre>my_dictionary = {<br> "Name": "Fredrick D. Thomas",<br> "Occupation": "Electronic technician",<br> "Age": "34"<br>}</pre>
<p>You can access an item by referring to its key name:</p>
<pre>print(my_dictionary["Age"])</pre>
<p><samp>34</samp></p>
<p>You can add and modify values:</p>
<pre>my_dictionary["Country"] = "USA"<br>print(my_dictionary)</pre>
<p><samp>{'Name': 'Fredrick D. Thomas', 'Occupation': 'Electronic technician', 'Age': '34', 'Country': 'USA'}</samp></p>
<p>You can check dictionary methods at:</p>
<ul>
<li><a href="https://docs.python.org/3/tutorial/datastructures.html#dictionaries" target="_blank">Python Docs</a></li>
<li><a href="https://www.w3schools.com/python/python_ref_dictionary.asp" target="_blank">W3Schools</a></li>
</ul>
</section>
<section class="main-section" id="Conditions">
<header>
<h1>Conditions</h1>
</header>
<p>Conditions always return a Boolean value</p>
<table>
<caption>Logical Conditions</caption>
<tr>
<td>Equals</td>
<td><code>a == b</code></td>
</tr>
<tr>
<td>Not Equals</td>
<td><code>a != b</code></td>
</tr>
<tr>
<td>Less than</td>
<td><code>a < b</code></td>
</tr>
<tr>
<td>Less than or equal to</td>
<td><code>a <= b</code></td>
</tr>
<tr>
<td>Greater than</td>
<td><code>a > b</code></td>
</tr>
<tr>
<td>Greater than or equal to</td>
<td><code>a >= b</code></td>
</tr>
</table>
<p>Let's see how to write a condition:</p>
<pre>a = 100<br>b = 50<br><br>if a > b:<br> print("a is greater than b")</pre>
<p><samp>a is greater than b</samp></p>
<p>When the <var>b</var> variable is greater than the <var>a</var> variable we can use <code>else</code>. Let's see an example:</p>
<pre>a = 50<br>b = 100<br><br>if a > b:<br> print("a is greater than b")<br>else:<br> print("b is greater than a")</pre>
<p><samp>b is greater than a</samp></p>
<p>But with this conditional statement, when <var>a</var> and <var>b</var> are equal, the program will return <samp>b is greater than a</var></samp> because the condition returns <code>false</code> in that case. We can solve this with <code>elif</code>, it's a second condition in case the first condition is not met. Let's see an example:</p>
<pre>a = 50<br>b = 50<br><br>if a > b:<br> print("a is greater than b")<br>elif a == b:<br> print("a and b are equals")<br>else:<br> print("b is greater than a")</pre>
<p><samp>a and b are equals</samp></p>
<p>If you want to combine many conditional statements, you can use the <code>and</code> keyword. Let's see an example:</p>
<pre>a = 50<br>b = 50<br>c = 40<br><br>if a > c and b > c:<br> print("a and b are greater than c")<br>else:<br> print("Nothing")</pre>
<p><samp>a and b are greater than c</samp></p>
<pre>a = 50<br>b = 30<br>c = 40<br><br>if a > c and b > c:<br> print("a and b are greater than c")<br>else:<br> print("Nothing")</pre>
<p><samp>Nothing</samp></p>
<p>If you want to combine many conditional statements and <u>at least one</u> of those must be met, you can use the <code>or</code> keyword. Let's see an example:</p>
<pre>a = 50<br>b = 30<br>c = 40<br><br>if a > c or b > c:<br> print("a, b or both are greater than c")</pre>
<p><samp>a, b or both are greater than c</samp></p>
<p>You can use conditions to check if there is a value in a list:</p>
<pre>my_list = ["Literature" , "Music" , "Films" , "TV" , "Videogames"]<br><br>if "Music" in my_list:<br> print("Yes, Music is in the list")</pre>
<p><samp>Yes, Music is on the list</samp></p>
</section>
<section class="main-section" id="For_Loops">
<header>
<h1>For Loops</h1>
</header>
<p><code>for</code> loops are used when you have a block of code that you want to repeat a fixed number of times. For example:</p>
<pre>for x in range(5): # You can rename the `x`<br> print("Hi")</pre>
<p><samp>Hi<br>Hi<br>Hi<br>Hi<br>Hi</samp></p>
<p>Instead of the <code>range()</code> function, you can pass a list, tuple... The number of iterations depends on the number of elements in the collection:</p>
<pre>animals = ("cat" , "dog")<br><br>for animal in animals:<br> print(animal) # `animal` -> element of an iteration</pre>
<p><samp>cat<br>dog</samp></p>
</section>
<section class="main-section" id="While_Loops">
<header>
<h1>While Loops</h1>
</header>
<p><code>while</code> loops are used when you have a block of code that you want to repeat infinitely or as long as a Boolean value is truthy. For example:</p>
<pre>while 4 < 10:<br> print("Hi")</pre>
<p><samp>Hi<br>Hi<br>Hi<br>Hi<br>Hi<br>Hi<br>Hi<br>Hi<br>Hi<br>...</samp></p>
<p>We can use the <code>break</code> statement to stop the loop even if the <code>while</code> expression is truthy:</p>
<pre>x = 1<br><br>while x < 10:<br> print("Hi")<br> x += 1<br> if x > 2:<br> break</pre>
<p><samp>Hi<br>Hi</samp></p>
</section>
<section class="main-section" id="Functions">
<header>
<h1>Functions</h1>
</header>
<p>A function is a block of code that only runs when it is called. For example:</p>
<pre>def my_function():<br> print("Hello")<br><br>my_function()</pre>
<p><samp>Hello</samp></p>
<p>You can add arguments:</p>
<pre>def sum(n1, n2):<br> print(n1 + n2)<br><br>sum(3, 5)</pre>
<p><samp>8</samp></p>
<p>If you don't know how many arguments you will need. You can add a <code>*</code> before the parameter name:</p>
<pre>def sum(*nums):<br> print(nums[3] + nums[5])<br><br>sum(2, 5, 7, 8, 4, 1)</pre>
<p><samp>9</samp></p>
<p>You can use the <code>return</code> statement to return a value:</p>
<pre>def multiply_by_3(number):<br> return number * 3<br><br>print(multiply_by_3(5))<br>print(multiply_by_3(7))<br>print(multiply_by_3(2))</pre>
<p><samp>15<br>21<br>6</samp></p>
</section>
<section class="main-section" id="Classes">
<header>
<h1>Classes</h1>
</header>
<p>Python, like other programming languages, is an <u>object-oriented programming language</u>. You can create an object with classes. Classes are object constructors. Let's see an example:</p>
<pre>class Car:<br> wheels = 4<br><br>my_car = Car()</pre>
<p>We have created an object called <var>my_car</var> with the <var>Car</var> class.</p>
<p>We can print the value of the <var>wheels</var> property:</p>
<pre>print(my_car.wheels)</pre>
<p><samp>4</samp></p>
<p>With the <code>__init__</code> method we can assign values to objects:</p>
<pre>class Battery:<br> def __init__(self, voltage, size):<br> self.voltage = voltage<br> self.size = size<br><br>my_battery = Battery(1.5, "AA")</pre>
<p>We can create a function inside a class:</p>
<pre>class Battery:<br> def __init__(self, voltage, size):<br> self.voltage = voltage<br> self.size = size<br> def get_info(self):<br> print(self.voltage, self.size)<br><br>my_battery = Battery(1.5, "AA")<br>my_battery.get_info()</pre>
<p><samp>1.5 AA</samp></p>
<p>We can modify the properties of an object:</p>
<pre>my_battery.voltage = 3</pre>
<p>We can delete a property or an object with the <code>del</code> statement:</p>
<pre>del my_battery.size</pre>
</section>
<section class="main-section" id="References">
<header>
<h1>References</h1>
</header>
<ul>
<li><a href="https://docs.python.org/3/" target="_blank">Python Docs</a></li>
<li><a href="https://wiki.python.org/moin/" target="_blank">Python Wiki</a></li>
<li><a href="https://www.w3schools.com/python/" target="_blank">W3Schools</a></li>
</ul>
</section>
</main>
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