Getting started with Python - Reading Time: 6 Mins

Introduction

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Since it's the start of the New Year. I thought of writing a tutorial. For anyone interested to learn Python to start their journey to get a job with it or automate your tasks.

Getting Started

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Let's head on down to Repl.it to create your new repl with Python by selecting new repl button and use the dropdown to select Python.

create new repl

Do you have something like this?

main screen

Now let us start with your first code and run it on Repl.it.

Let us enter the codes here in the middle under the file name called main.py:

print('Hello World')

The print statement is used to display words & numbers on your screen. It could be used for debugging purposes as well as you go along in programming in Python.

Great!! Now let us run it by clicking on the run button!!! Don't be shy!!! Does it look like this?

hello world

Awesome!!! Give yourself a pat on the back for a job well done.

Variable

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A variable is a container which you could store something on your computer's memory.

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Think of it like it is a bottle or a box created by you. It could be used to just store numbers, letters, date and many others.

Here is how it look like to create a variable:

a = 'Hello World'

The a is the name of the variable, think of it like it's a label for your box.

For the Hello World, it is the content that is stored in a. Which is called a string data type that stores letters, characters or text in it.

print(a)

Now try running it on Repl.it, it should look like just two lines of code in Repl.it.

a = 'Hello World'
print(a)

variable

Data Types

Data types are a list of categories on how data is stored in a variable. Here are some common data types, you will be using for Python or other programming languages:

  • Integer (int)- whole numbers
a = 1
b = 11002
c = -11002
  • Float (float) - floating-point or decimal numbers
a = 1.22
b = 3.221
c = -2918.111
  • Boolean (bool) - True which represents 1 or False which represents 0. This is borrowed from the binary number system.
a = True
b = False
  • Mapping (dict) - It is called a dictionary that uses keys as a label to get the content. In the example below, a is the key that retrieves a value called "apple".
book = {'a': "apple", 'b': 'banna', 'c': 'cat'}
print(book['a'])
  • Sequence ( tuple or list) - Both tuple & list are different ways to store data.

It uses an index to retrieve a value based upon the position of how it is arranged.

It starts with 0 in the first place on the left with an increment of 1 toward the next position.

a = (1, 2, 3, 4, 5) # tuple
b = [1, 2, 3, 4, 5] # list

print(a[0])
print(b[2])

Functions

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Functions are basically pieces of reusable code that are packed nicely in a package. This is how it is declared:

def magic():
	print('Hello World')

You can even add in variables as an input for your functions to process it. It is called parameters or arguments:

def calculate_area(length, breath):
	return length * breath 

Now let us call the function, by using the name of the function with open and close curly braces like this ():

def magic():
	print('Hello World')

def calculate_area(length, breath):
	return length * breath 

magic()
print(calculate_area(5,10))

Now let us try and run it in Repl.it.

functions

If & Else Statements

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The If and Else statement is a checklist you had made that starts from the top to the bottom.

If

The if statement checks for certain conditions that meets the expectation and proceeds to execute the piece of code that under the specific condition

You can think of if statement like asking a question and you reply if it meets your expectation. Here is an example of an if statement:

area = 24

if (area == 24):
	print('Area is 24')

if (area == 12):
	print('Area is 12')

The code with == means equals in Python. Therefore there are two if statements.

The first if statement checks if area is equal to 24, whereas another is checking if the area is 12.

Else

For the else statement, it is sort of like the backup plan when your if statement fails to get the correct condition:

area = 24

if (area == 10):
	print('The area is 10')
else:
	print('The area is not 10')

Else If

An elif statement represents something like having multiple plans starting from the first to the last.

This is different from the previous two if statements. Since there is a flow which they depend on the if or elif to fail. Before proceeding to the next elif or else statement:

area = 24

if (area == 10):
print('The area is 10')

elif (area == 12):
	print('The area is 12')

elif (area == 20):
    print('The area is 20')

else:
print('Area is more than 12')

This is a way of programming called if-else-if ladder that makes decisions in your program.

For

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The for statement or for loop is used to repeat a piece of code multiple times.

Here is an example of how it looks like in declaring and creating a for loop statement:

for i in range(11):
	print(i)

Now try running this code before proceeding with my explanation. Does it look like this?

forloop1

Alright, let me explain how this is done. The i is a variable. Think of it like it is the head of a crawling machine that grabs a value and keeps it temporary.

Now range is a function which returns a sequence of numbers. This starts with 0 (default) and increments by 1 till the last position.

This essentially repeats a code for 11 times which is the number that you had included in the range function for the for loop.

To customise your for loop, you can make changes to the range to provide you with a different result:

for i in range(1, 11):
	print(i)

Now try running again what do u see? Is it something like this 1?

forloop2

Now in the range, you had included 2 parameters. The first one 1 as the number for i to start and 11 as the ending which is why it returns 10 times.

You can control the increment as well instead of just the default 1 for the range function you can add a 3rd parameter that represents the increment in the right side.

for i in range(1, 11, 2):
    print(i)

forloop3

Conclusion

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Phew.....that was a lot of information to digest, congrats in making it through the end of the tutorial. I hope you had gained useful insights into it.

Lastly, I suggest that you jump over to Clever programmer's 11 hrs tutorial on Python for the absolute beginner. He offers tons of insights to get a job or getting your feet wet as a Python freelancer.

Reference