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<div id="content">
<h1 class="title">Python Key Skills</h1>
<div id="table-of-contents">
<h2>Table of Contents</h2>
<div id="text-table-of-contents">
<ul>
<li><a href="#sec-1">1. Python Key Skills</a>
<ul>
<li><a href="#sec-1-1">Learn It - convert from number data type to string</a></li>
<li><a href="#sec-1-2">Learn It - comparing values and comparators</a></li>
<li><a href="#sec-1-3">Learn It - create an array of numbers or strings</a></li>
<li><a href="#sec-1-4">Learn It - array index and get an item from an array</a></li>
<li><a href="#sec-1-5">Learn It - swap the positions of two items in an array</a></li>
<li><a href="#sec-1-6">Learn It - generate random numbers</a></li>
<li><a href="#sec-1-7">Learn It - Find out of a number is a mulitple of other number</a></li>
</ul>
</li>
</ul>
</div>
</div>

<div id="outline-container-sec-1" class="outline-2 activity">
<h2 id="sec-1"><span class="section-number-2">1</span> Python Key Skills</h2>
<div class="outline-text-2" id="text-1">
</div>
<div id="outline-container-sec-1-1" class="outline-3 learn">
<h3 id="sec-1-1">Learn It - convert from number data type to string</h3>
<div class="outline-text-3" id="text-1-1">

<div class="org-src-container">

<pre class="src src-Python">myName = "Jack"   # A string
myAge = 5         # A number

# To convert myAge to a string so we can make a longer string to display:
print(myName + " : " + str(myAge))
</pre>
</div>
</div>
</div>

<div id="outline-container-sec-1-2" class="outline-3 learn">
<h3 id="sec-1-2">Learn It - comparing values and comparators</h3>
<div class="outline-text-3" id="text-1-2">
<ul class="org-ul">
<li>Comparators check if a value is (or is not) equal to, greater than (or equal to), or less than (or equal to) another value. 
</li>
<li>The result of comparator operation is always a Boolean vale - <code>True</code> or <code>False</code>
</li>
<li>Depending on the comparing outcome, the program then decide what to do next.
</li>
<li>Python has the following comparators: 
<ul class="org-ul">
<li>logical operators
<ul class="org-ul">
<li>Equality, ==
</li>
<li>Not equal, !=
</li>
<li>Greater Than, &gt;
</li>
<li>Less Than, &lt;
</li>
<li>Greater than or equal to, &gt;=
</li>
<li>Less than or equal to, &lt;=
</li>
</ul>
</li>
<li>Boolean operators: and, or, not
<ul class="org-ul">
<li><code>and</code>: evaluates to True when both clauses (expressions) are True
</li>
<li><code>or</code>: evaluates to True when either of the expressions are True
</li>
<li><code>not</code>: evaluates to True when the expression is False. Evaluates to False when the expression is True.
</li>
</ul>
</li>
</ul>
</li>
<li>Example usages of comparators
</li>
</ul>
<div class="org-src-container">

<pre class="src src-Python">hunger = True
numberOfPizza = 5
drink="fizzyPop"

if numberOfPizza &gt;= 3:
   print("Have some pizza, since we have 3 or more")
else:
   print("You cannot have any pizza")


if hunger == True and numberOfPizza &gt;= 1:
   print("You are hungry, and there is at least one pizza")
else:
   print("Either you are not hungry or the food is not pizza")

if not drink == "fizzyPop":
   print("No drink for me.")

#The above is same as:
if drink != "fizzyPop":
   print("No drink for me.")
</pre>
</div>
</div>
</div>

<div id="outline-container-sec-1-3" class="outline-3 learn">
<h3 id="sec-1-3">Learn It - create an array of numbers or strings</h3>
<div class="outline-text-3" id="text-1-3">

<div class="org-src-container">

<pre class="src src-Python"># An array of numbers
testScores = [98, 78, 65, 89, 75]

# An array of strings
names = ['Jack', 'Kerry', 'Julia', 'Matthew', 'David']
</pre>
</div>
</div>
</div>


<div id="outline-container-sec-1-4" class="outline-3 learn">
<h3 id="sec-1-4">Learn It - array index and get an item from an array</h3>
<div class="outline-text-3" id="text-1-4">
<ul class="org-ul">
<li>Each individual data pieces is called an item
</li>
<li>Each item has a position number called <code>index</code>
</li>
<li>For the following array, names, "Jack" is at index 0.
</li>
<li>To get "Jack", you use <code>names[0]</code>
</li>
</ul>
<div class="org-src-container">

<pre class="src src-Python"># An array of strings
names = ['Jack', 'Kerry', 'Julia', 'Matthew', 'David']
</pre>
</div>


<div class="figure">
<p><img src="./img/arrayIndex.png" alt="arrayIndex.png" />
</p>
</div>
</div>
</div>
<div id="outline-container-sec-1-5" class="outline-3 learn">
<h3 id="sec-1-5">Learn It - swap the positions of two items in an array</h3>
<div class="outline-text-3" id="text-1-5">
<ul class="org-ul">
<li>Swap the position of "Jack" with "Julia"
<ol class="org-ol">
<li>Method 1: use a temporary variable 
<div class="org-src-container">

<pre class="src src-Python">names = ['Jack', 'Kerry', 'Julia', 'Matthew', 'David']

temp = names[0]
names[0] = names[2]
names[2] = temp
</pre>
</div>
</li>
<li>Method 2: in place swap
<div class="org-src-container">

<pre class="src src-Python">names = ['Jack', 'Kerry', 'Julia', 'Matthew', 'David']

names[0],names[2] = names[2],names[0]
</pre>
</div>
</li>
</ol>
</li>
</ul>
</div>
</div>
<div id="outline-container-sec-1-6" class="outline-3 learn">
<h3 id="sec-1-6">Learn It - generate random numbers</h3>
<div class="outline-text-3" id="text-1-6">
<ul class="org-ul">
<li>In Python, to generate random numbers, you use a module call <b>random</b>
</li>
<li>At the start of your program/code, you need to import the module <b>random</b>
<ol class="org-ol">
<li>exmaple 1: generate a random whole number from 0 up to a limit 
<div class="org-src-container">

<pre class="src src-Python">import random

randomNumber = random.randrange(100)
# The above code picks a random number between 0 and 99

randomNumber = random.randrange(2, 10, 2)
# The above code picks a random number from 2, 4, 6, 8 (goes up by 2)
</pre>
</div>
</li>

<li>exmaple 2: generate a random number between a range 
<div class="org-src-container">

<pre class="src src-Python">import random
randomNumber = random.randint(1, 100)
# The above code picks a random whole number between 1 and 100

randomNumber = random.randint(50, 100)
# The above code picks a random whole number between 50 and 100
</pre>
</div>
</li>

<li>example 3: pick a random item from a list
<div class="org-src-container">

<pre class="src src-Python">import random

names = ['Jack', 'Kerry', 'Julia', 'Matthew', 'David']

randomIndex = random.randrange(len(names))

print("The random picked name is: ", names[randomIndex])
</pre>
</div>
</li>
</ol>
</li>
</ul>
</div>
</div>
<div id="outline-container-sec-1-7" class="outline-3 learn">
<h3 id="sec-1-7">Learn It - Find out of a number is a mulitple of other number</h3>
<div class="outline-text-3" id="text-1-7">
<ul class="org-ul">
<li>In maths, we know that if a number A is a multiple of number B, it means A/B will not have a remainder - the remainder is 0.
</li>
<li>In Python, there is an operator for computing remainder conveniently.  The operator is called <code>modulo</code> which is <code>%</code>
</li>
<li>Example 1
</li>
</ul>
<pre class="example">
A=40
B=5
A%B will output 0
</pre>

<ul class="org-ul">
<li>Example 2
</li>
</ul>
<pre class="example">
A = 12
B= 9
A%B will output 3 since 12 only contains one 9, the remainder is 12- 1 x 9=3
</pre>

<ul class="org-ul">
<li>Example 3
</li>
</ul>

<pre class="example">
A = 9
B= 12
A%B will output 9 since 9 contains zero 12, the remainder is 9 - 0 x 12 = 9
</pre>

<ul class="org-ul">
<li>This remainder operator can be used to check if a number is even or odd
</li>
</ul>
<pre class="example">
num = int(input("Give me a number: "))

if num % 2 == 0:
   print("It's an even number")
else:
   print("Not an even number")
</pre>
</div>
</div>
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