Python for Beginners - Learn Python in 1 Hour
Programming with Mosh
Python Programming Tutorial
In this Python tutorial, you'll learn everything you
... [Show More] need to start programming in Python. This tutorial is perfect for data science, machine learning, and web development. No prior knowledge in Python or programming is required as everything will be taught from scratch. I'm Mosh Hamadani, and I've taught millions of people how to code through this channel. If you're new here, make sure to subscribe as I upload new videos every week. Let's jump in and get started.
What is Python?
Python is a multipurpose programming language that can be used for a variety of different tasks, such as automation, web development, and data science.
You can use Python in automation to automate repetitive tasks and save time and increase productivity.
You need to install a code editor to write your own Python code.
You can build amazing websites powered by Python.
We'll be using PyCharm as our code editor in this tutorial. When you open PyCharm for the first time, you have to configure a few settings, but we can skip that for now and set defaults. Let's create a new project and collapse the project window to give more space. We can then print a message on our application window.
Running Python Code
To run Python code in PyCharm, we go to the run menu and select run, or use the shortcut (ctrl+shift+r on a Mac). Then select the app to run, and the output will appear in the terminal window. Python is case sensitive so make sure to use the correct case when coding. We can declare variables, such as age and price, and assign them values. Python also has boolean values that can be true or false.
Now let's start coding!
age = 30
print(age)
price = 19.95
print(price)
Declare and Use Variables in Python
Here's a little exercise for you: imagine we want to write a program for a hospital, so we're going to check in a patient named John Smith. He's 20 years old and is a new patient. I want you to declare a few variables to store these values.
Use the comment section below to share your code.
Receiving User Input in Python
In Python, we have a built-in function called input() that we use to read a value from the terminal window. We can add a string argument to the function to prompt the user for input.
Let's write a simple program to demonstrate this:
name = input("What is your name? ")print("Hello, " + name)
When we run this program, it will prompt the user to input their name. Once a value is entered, the program will print the greeting message with the input value.
Data Types in Python
There are three main data types in Python: numbers, strings, and booleans.
Numbers - This includes integers and floating-point numbers.
Strings - This includes textual data.
Booleans - This includes True and False values.
Converting Data Types in Python
Python has several built-in functions for converting the types of our variables. For example, we have the int() function for converting a value to an integer:
birth_year = "1982"age = 2020 - int(birth_year)print("You are " + str(age) + " years old.")
In the above example, we use the int() function to convert the birth_year string to an integer so we can subtract it from the current year.
We also have the float() function for converting a value to a float:
num = "10.5"float_num = float(num)print(float_num)
In the above example, we use the float() function to convert the num string to a floating point number.
Type Conversion in Python
In programming languages like Python, there are times when you need to convert a variable from one type to another. In this tutorial, I'll show you a bunch of cool things you can do with strings using Python for beginners.
In Python, the index of the first character in a string is 0. So, when we run this program, you're going to see 1 on the terminal because the index is 1.
print("Hello World"[1]) # Output: e
The float function is used to convert a string to a float value.
first = float(input("Enter the first number: "))
We can also change this expression to first + second, which is another way to write this piece of code.
The lower method is used to convert a string to lowercase or to find a character or a sequence of characters.
string = "Hello World"print(string.lower()) # Output: hello worldprint(string.find('o')) # Output: 4print(string.replace('o','a')) # Output: Hella Warld
The in operator can be used to check if a string contains a character.
string = "Python is a programming language for beginners."print('language' in string) # Output: True
Arithmetic Operators in Python
Python has various arithmetic operators that we can use, such as addition (+), subtraction (-), multiplication (*), and division (/).
print(10 + 3) # Output: 13
We also have an augmented assignment operator in Python that means incrementing a variable by a value.
x = 5x += 3 # Output: 8
Operator precedence in Python is similar to math, but we can always use parentheses to change the order of operations.
x = 10 + 3 * 2 # Output: 16
Multiplication and division have a higher order, so they are evaluated first. That's why the answer is 16.
x = 10 + 3 / 2print(x) # Output: 11.5
When we print x, we get 11.5.
x += 3print(x) # Output: 14.5
When we run x += 3, we get 14.5 as the result. When we run x == 13, it will store False in the x variable.
x = 1000 # Output: 1000
Python programmers use comparison operators to evaluate values in Python programs. These operators are important for comparing values and evaluating certain conditions. They help to build complex rules and conditions. Another set of important operators are the logical operators, used to evaluate complex rules.
Comparison Operators
Python uses comparison operators to evaluate values and build complex rules. The following are comparison operators in Python:
Equal to: ==
Not equal to: !=
Greater than: >
Less than: <
Greater than or equal to: >=
Less than or equal to: <=
Logical Operators
Python uses logical operators to evaluate complex rules. The following are logical operators in Python:
And operator: and
Or operator: or
Not operator: not
Python can perform complex evaluations by applying multiple logical and comparison operators to the expressions.
If Statements
If statements in Python are used to make decisions in the program. For example, you can declare a variable called temperature and depending on its value, print different messages on the terminal.
To represent a block of code in Python, we use indentation instead of curly braces. If the code is not indented, it will not be executed.
In Python, there are three logical operators:
The logical or operator returns true if at least one of the expressions are true
The logical and operator returns true if both the expressions are true
The logical not operator inverts any value that it is given
Example
Let's take an example to understand the usage of these operators:
temperature = 25 if temperature > 30: print("It's a hot day") elif temperature > 20 and temperature <= 30: print("It's a nice day") elif temperature > 10: print("It's a bit cold") else: print("It's a cold day")
In this sample code, if the temperature is:
Greater than 30, it's a hot day
Between 20 and 30, it's a nice day
Greater than 10, It's a bit cold
Less than or equal to 10, it's a cold day
Remember, the code will only execute if the expression inside the if or elif statements are true. If none of the conditions are true, the code will not be executed.
Comments in Python are added using the hash (#) symbol. Anything following the hash symbol will be ignored by Python.
Python Exercise
Let's spend 5 minutes on this exercise. You can use the comment box below to share your code with others. When you're done, come back and see my solution.
The code is in Python, a case-sensitive language. So, we need to convert a given string to uppercase. Earlier, we talked about string methods. We can see all the available functions or methods in a string object by typing dot. We use the upper method to convert the string to uppercase, which returns a new string.
If the given string includes a lowercase "k", we should convert the weight to pounds and print it on a terminal. We declare a variable called "converted," get the weight, divide it by 0.45 to convert it to pounds, and print the weight in pounds. To terminate this block, we add "is" and concatenate it with "converted."
If the "k" condition is not true, that means the weight was entered in pounds. To convert it to kilograms, we declare a variable called "converted," set it to weight times 0.45, and print the weight in kilograms. To terminate this block, we add "in kilograms" and concatenate it with "converted."
While Loops in Python
In Python, we use while loops to repeat a block of code multiple times. We can use this to print the numbers 1 to 1 million times in Python. But, writing 1 million lines of code isn't a good approach. We can use a while loop and print the numbers using a loop instead.
In every iteration of the loop, the value of "i" is incremented by one. We can use the multiplication operator to repeat a string based on the value of a number in Python, but we can't concatenate a number to a string. In this case, we multiply a number by a string to repeat that string. We see one extra asterisk in every iteration.
It will never terminate, and our program will continue running until it runs out of memory. So, we need to add a break statement to terminate the loop after a certain number of iterations.
About the Instructor
If you want to learn more about Python, you may want to look at the Python course offered by the instructor. It comes with a 30-day money-back guarantee and a certificate of completion, which you can add to your resume. You can find plenty of courses on web and mobile development on the instructor's online coding school at codewithmosh.com.
In Python, negative indices can be used to access elements in a list. The elements in the list are separated by commas. To change an object at a specified index, we use an assignment statement. When we use colon notation, Python returns a new list that excludes the last index. This is how lists are used in Python:
To get items in a list using negative index
To change an item at a given index
To access elements from the start index up to the end index but exclude the end
In Python, objects like your phone, bicycle, or TV remote control have strengths that allow you to operate them. They also have strengths in the real world. Similarly, Python returns a list with an index that includes the elements at index 0, 1, and 2.
If we type a string and press dot, we can see all the available functions or methods in a string object in Python. Lists are also objects, so they have various methods for adding or removing items.
To insert an element in the middle, use the insert() method. If you want to remove all items in the list, use the clear() method.
To add a new element at the end of the list, use the append() method. When you want to iterate over a list and access each item individually, use the built-in len() function.
The for loop and while loop can both be used to iterate over a list with each item printed on a new line. The implementation using the for loop is the shortest and easiest to understand.
The range function in Python is a built-in function that allows us to create a range of numbers. We can pass a value, such as 5, and it will return a range object. Using a for loop, we can iterate over the values in this list.
Tuples in Python are similar to lists, and we can use for loops with any object that represents a sequence of objects, including tuples. We can even use the range function to iterate over a sequence of numbers by specifying the step (e.g. 2 to jump two numbers at a time).
However, tuples are immutable, meaning we cannot change them once we create them. We can also use other methods that start with an underscore, called magic methods, which are an advanced topic covered in detail in my complete Python programming course available on my website.
If you're interested in learning more about Python, you can check out my Python course on codewoodmarch.com, which covers everything from the basics to more advanced concepts in web and mobile development, and comes with a 30-day money-back guarantee and a certificate of completion to add to your resume.
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