Thinking Like a Programmer•Interactive notebook lesson•Free

Introduction to python

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The intention here is to teach the basics of python programming language in a beginner friendly way. So, by no means will these tutorials be comprehensive. But I do hope these basics will help readers understand the fact that we want to use python as a tool for machine learning and not as a programming language.

Data Types

Integer: 1, 2, 10
Decimal numbers: float: 1.0, 2.1, 10.5
Boolean: True, False
Nonetype: Null values
String: "It is some character sequence"

Typecast

Implicit type casting
Explicit type casting

Operators

Arithmetic
Assignment
Comparison
Logical
Identity
Membership
Bitwise

Data Structures

Lists
Tuples
Dictionaries
Set
Chained Sequences: lists, tuples, chained dictionaries
Indexing

Conditional statements

Code block
if
if else
if elif else

Loops

for loop
while loop
nested loops
nested loops with conditional statements

Functions

Inbuilt functions
Custom functions
return keyword
Arguments: positional, keyword, kwargs
Parameters: Default
Tuple packing / unpacking
return vs yield keyword
Anonymous functions: lambda functions
Scope: local environment vs global environment
Generators

Debugging

Classes, methods and objects

Exception Handling

User Input

String Formatting

File Handling

External Libraries

re
os
Numpy
Pandas
Scipy
Matplotlib
Seaborn
Plotly
Scikit-Learn
NLTK
Opencv
Tensorflow

Programming language, no matter which one, is just a tool to complete some sort of objective. If our objective is to perform some mathematical operations, we could choose a programming language as a calculator. There exists multiple programming languages.

Python is just of these programming languages. One could argue that one language is better than the others, but its about our end objective that really defines which programming language we should choose.

There's a saying in programming community, "If all you have is a hammer, all you would ever see is a nail". And for that reason, as we learn and grow, we eventually practice more than one programming language.

So, there exists multiple programming language to solve different types of problems. If our objective is to create a web page, we could use python, c# etc. There are dedicated softwares using which we can create websites without even programming at all.

Its just that a lot of people use python now and if we learn the same language as they do, it helps us to communicate with them therefore making our learning process easier.

Well, there are some minor differences between different programming languages (like the syntax), but the logic is the same between them. They all have the concept of data types, variables, functions, conditionals, and so on.

If at this point you've heard about AI (artificial intelligence) then python is a good starting point because a lot of experts have made a lot of functionalities for python. Its not like, these functionalities couldn't be developed for other programming languages, its just that, if majority speaks english, then it makes sense to write books in english so that the particular book could reach to the masses.

Jupyter Notebook Basics

Text cells
Code cells
Command Mode
Edit Mode
Shorcuts

Google colab uses ipy kernal, which is almost like a python engine, except that it gives a little more use-ablity than the standard python kernal.

Text / Markdown Cells

In Jupyter Notebooks, we can also create text cells. These cells are used for writing notes, explanations, headings, and other content alongside our code.

Python does not execute anything inside a text cell. Instead, the text is displayed as formatted content.

Text cells use Markdown, a simple syntax for formatting text. They also support LaTeX, which is commonly used to write mathematical notation and equations.

For example, we can write a mathematical expression like:

$$ \text{Mean Squared Error} $$

Or a more complicated equation:

$$ \text{error}(\theta0,\theta1) =

\frac{1}{2m} \sum{i=0}^{m-1} \left( (h{\theta0} + h{\theta1}x1^{(i)}) - y^{(i)} \right)^2 $$

This means we can keep our code, explanations, mathematical equations, and even images together in the same Colab notebook.

That makes notebooks especially useful for learning and experimenting, because we can explain what our code is doing right next to the code itself.

We can even add images to our Markdown cells when they help explain an idea.

Code Cells

Code cells are where we write our python code. Simple enough, right.

Cell execution: Press the run/play button located on the leftmost side of the cell

Keyboard shortcuts

Important ipynb notebook (colab) shortcuts

shift (hold) + enter (press): To execute a cell, hold the shift key on your keyboard and press enter to execute a cell. The cell will be executed and colab will take the user to the cell below. If the next cell doesn't exist, colab will create one.

ctrl (hold) + enter (press): Execute the current cell and stay on it

alt (hold) + enter (press): Execute current cell, create a cell below and take the user to the cell below.

Command mode

If you are writing something inside a colab cell, press esc key to get into command mode. From there, you could use following keyboard shortcuts.

To add cell above: press a

To add cell below: press b

To delete current cell: d,d Press d two times in succession

To undo / retrieve deleted cell: z,z

Specific to ipy kernal of jupyter notebook (not for colab)

Change cell type to markdown: m

Change cell type to code: y

Change cell type to raw text: r

Edit mode

If you're typing in a cell, you're in edit mode. If you're in command mode, press enter on a cell to get into the edit more.

Python basics

Programming language as a calculator

Codepython

10 + 2

Output

Codepython

10 * 2

Output

Codepython

10 / 2

Output

5.0

Codepython

10 - 2

Output

square

Codepython

10 ** 2

Output

cubic power of 10

Codepython

10 ** 3

Output

Python ignores whitespace between different objects in same line
Python uses new lines to complete a command
Python uses indentation to separate a certain code block from the rest of the code.

We'll talk about code block and objects later as well.

Variables

We could take any integer or number and give it a name. That data will be stored as a name and that name would be remembered by python.

Let's take an integer 10 and assign it to the variable a

Codepython

a = 10

New ability unlocked: print() function

Use: Print to console

print() function takes some input and outputs it into the python console. We will study functions in detail later on.

We will now print the value assigned to a.

Codepython

print(a)

Output

Codepython

b = 2

Codepython

print(b)

Output

Codepython

print(a + b)

Output

Codepython

print(a - b)

Output

Comments

Use: Python will ignore every word written after the # sign

Codepython

# Comments: useful to make notes
# The words that I'm writing here (after the # symbol)
# in the code cells are ignored by python

print(10) 

# print(20) # will not be printed in ouput as we are using the # symbol

Output

Best practices for the variable names

Variable name must start with a letter

Variable name should not start with a number

Variable names should only contain alpha-numerics or underscores (A-Z, a-z, 0-9, _)

Codepython

# We can choose any variable name but we have to watch out for some certain rules.

# Variable name must start with a letter
variable1 = 10     # is allowed

print(variable1)

# Variable name should not start with a number
# 10variable1 = 11    # is not allowed

# Variable names should only contain alpha-numerics or underscores (A-Z, a-z, 0-9, _)
our_first_variable = 12    # is Allowed
print(our_first_variable)

Output

10
12

Its generally a good practice to separate code chunks into different code cells for learning purpose. For final development purpose, we usually should copy all the code from different cells into a different python script (or a cell at the bottom) to ensure if everything in the script is working fine.

Codepython

a = 10
print(a)

# Whitespaces between different objects are ignored by python
# We'll talk about objects later as well

b= 2 # Notice: I'm intentionally using whitespaces irregularly here
print(b)

print(a+b)
print(a  -b)

Output

ipy kernal in notebooks (Colab) have an autoprint feature which autoprints the variable located at the most bottom code line

Codepython

Output

Codepython

a
b

Output

Codepython

a

b

a + b # value of a+b will get auto-printed by ipy notebooks (colab)

Output

Codepython

print(a)
print(b)
print(a+b)

Output

10
2
12

Finished this lesson?

Keep your place here, or save it across devices with an email link.

Saved in this browser. Save progress with email →

Thinking Like a Programmer•Interactive notebook lesson•Free

Introduction to python

No account is required. Learn the material, try the examples, and mark it complete when you are ready to move on. Sign in with email only if you want to save progress across devices.

Data Types

Integer: 1, 2, 10
Decimal numbers: float: 1.0, 2.1, 10.5
Boolean: True, False
Nonetype: Null values
String: "It is some character sequence"

Typecast

Implicit type casting
Explicit type casting

Operators

Arithmetic
Assignment
Comparison
Logical
Identity
Membership
Bitwise

Data Structures

Lists
Tuples
Dictionaries
Set
Chained Sequences: lists, tuples, chained dictionaries
Indexing

Conditional statements

Code block
if
if else
if elif else

Loops

for loop
while loop
nested loops
nested loops with conditional statements

Functions

Inbuilt functions
Custom functions
return keyword
Arguments: positional, keyword, kwargs
Parameters: Default
Tuple packing / unpacking
return vs yield keyword
Anonymous functions: lambda functions
Scope: local environment vs global environment
Generators

Debugging

Classes, methods and objects

Exception Handling

User Input

String Formatting

File Handling

External Libraries

re
os
Numpy
Pandas
Scipy
Matplotlib
Seaborn
Plotly
Scikit-Learn
NLTK
Opencv
Tensorflow

Its just that a lot of people use python now and if we learn the same language as they do, it helps us to communicate with them therefore making our learning process easier.

Jupyter Notebook Basics

Text cells
Code cells
Command Mode
Edit Mode
Shorcuts

Google colab uses ipy kernal, which is almost like a python engine, except that it gives a little more use-ablity than the standard python kernal.

Text / Markdown Cells

In Jupyter Notebooks, we can also create text cells. These cells are used for writing notes, explanations, headings, and other content alongside our code.

Python does not execute anything inside a text cell. Instead, the text is displayed as formatted content.

Text cells use Markdown, a simple syntax for formatting text. They also support LaTeX, which is commonly used to write mathematical notation and equations.

For example, we can write a mathematical expression like:

$$ \text{Mean Squared Error} $$

Or a more complicated equation:

$$ \text{error}(\theta0,\theta1) =

\frac{1}{2m} \sum{i=0}^{m-1} \left( (h{\theta0} + h{\theta1}x1^{(i)}) - y^{(i)} \right)^2 $$

This means we can keep our code, explanations, mathematical equations, and even images together in the same Colab notebook.

That makes notebooks especially useful for learning and experimenting, because we can explain what our code is doing right next to the code itself.

We can even add images to our Markdown cells when they help explain an idea.

Code Cells

Code cells are where we write our python code. Simple enough, right.

Cell execution: Press the run/play button located on the leftmost side of the cell

Keyboard shortcuts

Important ipynb notebook (colab) shortcuts

ctrl (hold) + enter (press): Execute the current cell and stay on it

alt (hold) + enter (press): Execute current cell, create a cell below and take the user to the cell below.

Command mode

If you are writing something inside a colab cell, press esc key to get into command mode. From there, you could use following keyboard shortcuts.

To add cell above: press a

To add cell below: press b

To delete current cell: d,d Press d two times in succession

To undo / retrieve deleted cell: z,z

Specific to ipy kernal of jupyter notebook (not for colab)

Change cell type to markdown: m

Change cell type to code: y

Change cell type to raw text: r

Edit mode

If you're typing in a cell, you're in edit mode. If you're in command mode, press enter on a cell to get into the edit more.

Python basics

Programming language as a calculator

Codepython

10 + 2

Output

Codepython

10 * 2

Output

Codepython

10 / 2

Output

5.0

Codepython

10 - 2

Output

square

Codepython

10 ** 2

Output

cubic power of 10

Codepython

10 ** 3

Output

Python ignores whitespace between different objects in same line
Python uses new lines to complete a command
Python uses indentation to separate a certain code block from the rest of the code.

We'll talk about code block and objects later as well.

Variables

We could take any integer or number and give it a name. That data will be stored as a name and that name would be remembered by python.

Let's take an integer 10 and assign it to the variable a

Codepython

a = 10

New ability unlocked: print() function

Use: Print to console

print() function takes some input and outputs it into the python console. We will study functions in detail later on.

We will now print the value assigned to a.

Codepython

print(a)

Output

Codepython

b = 2

Codepython

print(b)

Output

Codepython

print(a + b)

Output

Codepython

print(a - b)

Output

Comments

Use: Python will ignore every word written after the # sign

Codepython

# Comments: useful to make notes
# The words that I'm writing here (after the # symbol)
# in the code cells are ignored by python

print(10) 

# print(20) # will not be printed in ouput as we are using the # symbol

Output

Best practices for the variable names

Variable name must start with a letter

Variable name should not start with a number

Variable names should only contain alpha-numerics or underscores (A-Z, a-z, 0-9, _)

Codepython

# We can choose any variable name but we have to watch out for some certain rules.

# Variable name must start with a letter
variable1 = 10     # is allowed

print(variable1)

# Variable name should not start with a number
# 10variable1 = 11    # is not allowed

# Variable names should only contain alpha-numerics or underscores (A-Z, a-z, 0-9, _)
our_first_variable = 12    # is Allowed
print(our_first_variable)

Output

10
12

Codepython

a = 10
print(a)

# Whitespaces between different objects are ignored by python
# We'll talk about objects later as well

b= 2 # Notice: I'm intentionally using whitespaces irregularly here
print(b)

print(a+b)
print(a  -b)

Output

ipy kernal in notebooks (Colab) have an autoprint feature which autoprints the variable located at the most bottom code line

Codepython

Output

Codepython

a
b

Output

Codepython

a

b

a + b # value of a+b will get auto-printed by ipy notebooks (colab)

Output

Codepython

print(a)
print(b)
print(a+b)

Output

10
2
12

Finished this lesson?

Keep your place here, or save it across devices with an email link.

Saved in this browser. Save progress with email →

Find your way

Introduction to python

Contents

Jupyter Notebook Basics

Text / Markdown Cells

Code Cells

Keyboard shortcuts

Command mode

Edit mode

Python basics

Programming language as a calculator

Variables

Comments

Finished this lesson?

Introduction to python

Contents

Jupyter Notebook Basics

Text / Markdown Cells

Code Cells

Keyboard shortcuts

Command mode

Edit mode

Python basics

Programming language as a calculator

Variables

Comments

Finished this lesson?