Introduction to Python (Pt. 1)

Welcome to the exciting world of Python!

Programming is a way to tell your computer how to perform tasks by giving it specific instructions.

A programming library is a collection of code that someone else has written, that you can then use (so you don't have to reinvent the wheel).

We'll learn more about advnaced AI libraries in Python later in the course. Scikit-Learn and TensorFlow are two of the most popular for programming AI and Machine learning programming.

Your First Line of Python

Now let's jump into some programming!

print("I'm here! I'm coding!")

I'm here! I'm coding!

Basic Arithmetic Operations

Basic arithmetic operations are built into the Python langauge. Here are some examples. In particular, note that exponentiation is done with the ** operator.

a = 12
b = 2

print("a + b = ", a + b)
print("a time b = ", a*b)
print("a divided by b = ", a/b)
print("a raised to the power of b = ", a ** b)

a + b =  14
a time b =  24
a divided by b =  6.0
a raised to the power of b =  144

Working with Lists

Lists are a versatile way of organizing your data in Python. Here are some examples.

colors = ['red', 'blue', 'green']
print(colors[0])    
print(colors[2])    
print(len(colors))  

red
green
3

List Methods

Here are some other common list methods.

• list.append(elem) -- adds a single element to the end of the list.
• list.insert(index, elem) -- inserts the element at the given index, shifting elements to the right.
• list.sort() -- sorts the list in place (does not return it).

• list.remove(elem) -- searches for the first instance of the given element and removes it (throws ValueError if not present)

• list.pop(index) -- removes and returns the element at the given index.

• list.reverse() -- reverses the list in place (does not return it).

colors.append('yellow')         

colors.insert(0, 'white')
colors

['white', 'red', 'blue', 'green', 'yellow']

colors.sort()
colors

['blue', 'green', 'red', 'white', 'yellow']

colors.remove('orange')

---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-7-8f5c5a0abd98> in <module>
----> 1 colors.remove('orange')

ValueError: list.remove(x): x not in list

colors.remove('white')
colors

['blue', 'green', 'red', 'yellow']

colors.pop(8)

---------------------------------------------------------------------------
IndexError                                Traceback (most recent call last)
<ipython-input-9-8b4a362877f0> in <module>
----> 1 colors.pop(8)

IndexError: pop index out of range

colors.pop(2)

'red'

colors

['blue', 'green', 'yellow']

colors.reverse()
colors

['yellow', 'green', 'blue']