Python is among the most popular programming languages in the world. It is ranked high in different StackOverflow programming surveys each year. This article helps beginners familiarize themselves with the basic concepts of Python. According to the official documentation, Python is a high-level and general-purpose programming language.
It is a preferred programming language for many developers due to its wide range of libraries. Individuals can use these libraries to create complex applications rather than building everything from scratch. Other reasons why developers love Python is because of its simplicity, flexibility, and versatility. Today, Python is being used in upcoming fields such as machine learning and artificial intelligence.
What you will learn
In this tutorial, you will learn how to define and use the following elements:
- Lists and Arrays
For simplicity, we will be using IDLE (Integrated Development and Learning Environment) in this tutorial. IDLE is the default Python code editor and compiler. You can download it from here. Also, note that this tutorial is based on Python 3.9 rather than the 3.6 version.
Variables are simply declarations that are used to store certain values. For instance, the variable
name can hold the value of
John Smith. Several rules need to be considered when declaring variable names. For starters, a variable name cannot begin with a number.
2name = incorrect #incorrect
name = correct #correct
Variable names are case sensitive. This means that the variable
school is not the same as
Variables can hold different data types. This includes strings, integers, Booleans, long, lists, and arrays.
In Python, we do not need to declare the data type while writing a variable. This is because the code is compiled and interpreted later. The compiler will throw an error in case there is a mismatch in the data types.
Let’s talk about the different data types.
Strings are usually presented in a text format. We will declare a string variable, as shown below.
name = “john” school = “Alliance Francaise”
When we run
print(name), the output will be
These variables hold numeric values, as shown below.
math = 90 chemistry = 100 biology = 70
We can find the total of the variables above using the following statement.
The total is
A TypeError is thrown when you try to add a string to an integer, as shwon below.
var1 = "30" #string var2 = 20 #integer print(var1+var2)#type error
We can sum
var2 by converting
var1 to an integer using the
int() function. The following code will execute successfully.
var1 = "30" #string var2 = 20 #integer print(int(var1)+var2) # Output: 50
Make sure that the variable stores a value that can be converted to an integer before using the int() method.
There are only two Boolean values:
False. In other words, something can either be true or false. We declare these values, as shown below. Please note that Python is case sensitive.
isOn = True isChecked = False
bool() method can help convert a value to a boolean. The code snippets below showcase how a
bool() function can be used.
print(bool("abc")) #returns True print(bool(0)) #returns False
bool() function returns False when there are no parameters.
This data type consists of numbers that have a decimal place. A perfect example of a float variable is highlighted below.
Bmi = 45.7
Lists allow us to store numerous elements in a particular variable. For instance, we can have a list that stores all the student names in a class. We use
 to define a list.
students =  #list example
Elements in a list are usually separated by a comma, as shown below.
students = [“john”, “Mary Thomas”, “John Smith”]
Each element in the above
students list has an index. By default, the first index is 0. So the item at index  is
john, while the value at index
Mary Thomas. A list of integers will look as follows.
student_marks = [90, 78, 90, 78]
We can access different list functionalities using built-in functions. For instance, to add a value to the
student_marks list, we use the
student_marks.append("Guardian Angel") print(student_marks)
The above function adds
Guardian Angel at the end of the
When we print the list it shows:
#output [90, 78, 90, 78, 'Guardian Angel']
len(student_marks) to determine the length of the list. We use the
remove() function to delete something from the list. For instance, we can remove
90 from the
student_mark list as shown below.
In lists, negative indices allow us to count elements starting from the last one. For instance, the element with an index of
-1 in the above
student_marks list is
"Guardian Angel". The second last element
78 has an index of
Understanding functions or methods
Methods are quite critical in programming. They help store reusable code. This means that a person can call already declared methods rather than writing statements from scratch repeatedly. This saves significant time, that can be invested in other productive activities.
In Python, we use the
def keyword to declare a function. An example of a python method is shown below.
def readData(): print('success')
The above function prints
success when it’s invoked. We can also pass data to a method, perform some calculations, and return the results. This is demonstrated in the code snippet below.
def calculateTotal(chem, bio): return chem+bio print(calculateTotal(90,80))
calculateTotal method takes in two parameters (chem, bio). The function then returns the sum of the two values. It is important to take note of the data types when passing parameters. For instance, the
calculateTotal method will not work when we pass in a string as a parameter. This is because the program cannot sum up an integer and a string. As shown above, we can call the
calculateTotal method directly from our print statement.
return keyword ensures that the method returns a result after execution.
Note that a function can also call another method. This is illustrated below.
def readData(chem, bio): return chem+bio def getTotal(): print(readData(90,80)) #calls the readData method getTotal()
Loops are critical because they allow us to iterate through lists, check for different conditions, and continuously execute various statements. The main loops are
- For loops As noted, we can use a for loop to iterate through a list, as shown below:
student_list = [“John Doore”,”Matu Smith”] for x in student_list: print(x)
for loop above will print every item in the student_list.
- While loops A while loop can help us check for a particular condition. For instance, while something is true specific statements can be executed. Here is an example of a while loop in action.
isChecked = false while isChecked == true: print('Hallo there')
Note that the while loop above will be executed indefinitely until isChecked is set to false. You can press ctrl+c to stop the loop.
Classes are a vital component of object-oriented programming. When creating a class, you must use the
class keyword. Other elements are then nested in the class. Here is an example of a Python class.
class Farmer: # a class with the name farmer name = "John" # A variable produce = "1000kgs" # A variable farmer = Farmer() #instatiating the class as an object. print(farmer.name) # accessing the properties of the Farmer class.
Classes can help as group things with similar characteristics. We can also assign values to class variables using the
class Farmer: def __init__(self, farmername, produce): self.farmername = farmername self.produce = produce farmer = Farmer("Carry Sminson", "10,000kgs") print(farmer.farmername, farmer.produce)
In the above
Farmer class, the
self keyword represents an instance of an object. In other words, it allows us to access the different methods and attributes defined in the class.
You can also declare a method in a class and use it later, as shown below.
class Farmer: def __init__(self, farmername, produce): self.farmername = farmername self.produce = produce def printDetails(self): # Method print(self.farmername, self.produce) farmer = Farmer("Carry Sminson", "10,000kgs") farmer.printDetails()
We have learned how to define and use variables, methods, classes, loops, and lists from this tutorial. You can learn more about other concepts from here. The secret to becoming a Python expert is to regular practice.
Peer Review Contributions by: Saiharsha Balasubramaniam