Getting Started with Python

As part of your Data Analytics journey, you will have to build knowledge of Python.

In this post I am collecting some of the must know tricks to start your projects.

• The Python Site
• The Python Source Code at Github

Installing Python 🐍

Python is F/OSS and you can download it here.

sudo apt update
sudo apt install build-essential software-properties-common -y
sudo add-apt-repository ppa:deadsnakes/ppa
sudo apt update

sudo apt install python3.11 -y

Dont forget to add it to the PATH if you are on Windows - Then check the version with:

python --version

You can also start an interactive session and try it:

python
1+1

Dont forget to check how to install dependencies

Choosing IDE

• VScode or VSCodium
• Spyder - For DSc’s
• Thonny - For IoT
• Jupyter Notebook - Great for EDA

Python 101 for your Projects

Let’s make a recap on Python’s Data Structures:

Lists

Index-value pairs in Python. Their order is maintained, they are mutable, and allows duplicate values.

your_list = ['one', 'two', 'three']

your_list[0]

Dictionaries

Your key-value friend from now on. Remember that the dictionary is unordered and mutable, but the dictionary doesn’t allow duplicate values with the same key in it.

They are great to store large amounts of data for easy and quick access.

your_dictionary = {
                    'one': 1,
                    'two': 2,
                    'three': 3,
                    'four': 4
                }

You can access an element with:

your_dictionary['two']

Sets

The sets are an unordered collection of data types. These are mutable, iterable, and do not allow of any duplicate elements.

Remember that they can’t be indexed.

your_set = {"hello", "fantastic", "world", True, 1, 2}

your_set

Tuples

Tuples are used to store multiple items in a single variable.

A tuple is a collection which is ordered and unchangeable, also they allow duplicates.

They are more space efficient, as they are inmutable, the memory allocation is better handdled.

your_tuple = ("hello", "fantastic", "world")

See a particular value with:

your_tuple[0]

Loops

Non-Pythonic approach

i = 0
new_list= []
while i < len(your_list):
    if len(your_list[i]) >= 4:
        new_list.append(your_list[i])
    i += 1
print(new_list)

A more Pythonic approach would loop over the contents of names, rather than using an index variable.

Looping over the contents of a list

better_list = []

for item in your_list:
    if len(item) >= 4:
        better_list.append(item)
print(better_list)

Best - List Comprehension

# Print the list created by using list comprehension

best_list = [item for item in your_list if len(item) >= 4]
print(best_list)

Functions

Regular Functions

def my_function():
  print("Hello World")

my_function()

def my_function_a(x,y):
  return 5 * x + y

print(my_function_a(3,1))

You can also define functions in other python scripts and call them as:

from Z_Folder_with_UDF import my_function_a as udf 

With this approach you can have all your User Defined Functions clearly ordered.

Lambda Functions

your_lambda = lambda a : a + 1

print(your_lambda(5))

Or also, with multiple arguments

your_lambda = lambda a, b : a * b

print(your_lambda(2, 3))

Using them together

Here, we will be using the output of the UDF myfunc as the input of the lambda function:

def myfunc(n):
  return (lambda a : a * n)

mydoubler = myfunc(2) #here you use a

print(mydoubler(11)) #here you are using n as input

Classes

This is going to be a little bit tricky if you are not used to OOP.

But dont be scared, you dont need to be a master of Object Oriented Programming before completing your first project - Actually, it is something that you will learn on the way, as you need it.

Creating your first Class

class Your_Class:
  x = 1

p1 = Your_Class()
print(p1.x)

Important: the init() Function

All classes have a function called init(), which is always executed when the class is being initiated.

class Person:
  def __init__(self, name, age):
    #this function gets executed everytime you will create an object of the class Person
    self.name = name
    self.age = age

p1 = Person("Yosua", 31)

print(p1.name)
print(p1.age)

The str() Function

class Person:
  def __init__(self, name, age):
    self.name = name
    self.age = age  

  def __str__(self):
    return f"{self.name}({self.age})"

p1 = Person("Yosua", 31)

print(p1)

Methods - ‘Class’s Functions’

Methods are function that belong to the objects created of a certain Class.

class Person:
  def __init__(self, name, age):
    self.name = name
    self.age = age

  def myfunc(self):
    print("Hello my name is " + self.name + " and I am " + str(self.age))

p1 = Person("Yosua", 31)
p1.myfunc()

Document your work

You want to make sure that your work is understandable, so make sure you write proper comments in your code.

If you do this and also make sure that your code is modular enough (use UD’sF!), it is already a good start:

Docstrings

def add(num1, num2):
    """
    Add up two integer numbers.

    This function simply wraps the ``+`` operator, and does not
    do anything interesting, except for illustrating what
    the docstring of a very simple function looks like.

    Parameters
    ----------
    num1 : int
        First number to add.
    num2 : int
        Second number to add.

    Returns
    -------
    int
        The sum of ``num1`` and ``num2``.

    See Also
    --------
    subtract : Subtract one integer from another.

    Examples
    --------
    >>> add(2, 2)
    4
    >>> add(10, -10)
    0
    """
    return num1 + num2

FAQ

How to Install Python Dependencies?

• There are two main repositories for Python Packages:
  • The Python Package Index (PyPI): PyPI is the main repository for third-party Python software.
  • GitHub: a code hosting platform where developers can store and share their code. The Python organization on GitHub has several repositories that contain the official source code for the Python programming language, as well as documentation, tools, and other resources.

So we know from where we can get Python packages, but now: How to install them and their dependencies properly?

These are some popular ways to install Python dependencies and make sure that we can replicate the working code in other people’s computers.

conda create -n yourcondaenvironment python=3.11
conda activate yourcondaenvironment

which python

python -m pip install numpy
# $(which python) -m pip install numpy #to make sure it is installing it in this conda environment

conda search numpy 
conda install numpy

python -m venv myvirtualenv #create it

myvirtualenv\Scripts\activate #activate venv (windows)
source myvirtualenv/bin/activate #(linux)

deactivate #when you are done

pip install package_name
#pip install numpy
#pip install numpy==1.26.4

#pip show numpy #check the installed version

[tool.poetry]
name = "my_project"
version = "0.1.0"
description = "A sample Python project"
authors = ["Your Name <your.email@example.com>"]

[tool.poetry.dependencies]
python = "^3.6"
requests = "^2.25.1"

[build-system]
requires = ["poetry-core>=1.0.0"]
build-backend = "poetry.core.masonry.api"

poetry build

Understanding statistical distributions with Python

Poison

Normal

…