Python Tutorial for Absolute Beginners  - What Are Variables?

If you’re just getting started with Python or programming in general, then this article is for you! Here we’ll cover variables and data types in Python. Some programming languages are strongly typed, while others are weakly typed. Python is a weakly typed language. This means that you don’t need to explicitly specify the type of variable you want to create. You can just create one and it will be assigned a default type based on the value you give it when creating it. How do we know what type to use?

1. What are variables?

Variables are values that change. The speed of a car, the time of day, your weight, and the number of apples in a basket are all variables. You can change the value of a variable. For example, you can drive faster, wait longer, weigh less, or take more apples out of the basket.
As for data types, they describe the data you want to receive. So you can have integers, strings, numbers, lists, dicts, and some other things. These can be called “built” types, but we’ll talk more about this later. Now, we create a variable called y which starts out as always equal to “1” (the type of the object). This will create the default type for all instances of this variable. In other words, that's just one way of creating a default data type in Python. You can also have a named type, which is an extra data type you can create that will tell the types of things. This allows you to have things like integers that are named after their digits and even letters that are named after their first letter. Name-based typed data types are really helpful for ensuring that something is of the same type as another. Variables will follow this same rule, or the default one for all variables that have it, assigned by the language maintainer.
What do you need to know about defaults when you start using Python? Some languages require you to use a specific format to send data to the server. This is called a “delimited” or binary format. You need to send this format to your web service or desktop tool for it to be useful to them. Python doesn’t require this. You can send any data you want, in any shape, anyhow. Here’s a simple example:
Now that we’ve learned about defaults in Python, let’s talk about how to set them and get them to reset. Variables are set in two ways. The first way is to use the set() function.

2. How do we declare a variable in Python?

Python has two types of variables: one-dimensional and multi-dimensional arrays. It's important to understand that the syntax of declaring one-dimensional and multi-dimensional arrays is different. The syntax of declaring a one-dimensional array is as follows:

So, just take this one step at a time and learn this! Lastly, you’ll notice that there is a comma at the end of the colons. This means there could also be spaces before or after the comma. If you need to put spaces, they must be at the end of the array, as in the following example:

As a beginner, you’re going to have questions along the lines of “how do I create a 3-dimensional array?” I’m going to break this down into its basic components, so you can understand the basic building blocks of arrays:-

Let’s explore each element of the above example.

What is an item in a 2D array? There are many ways to access types of items, but the classic way is to use items of the same type in their place. This means that you simply add the item on one side of the array, and the corresponding item on the other side. To create the 3-dimensional array above, we could do:

What if we want to create an n-dimensional array? Then we need to access the n-1 elements of the array and add the corresponding items in their places on the other side of the array. This would be a more complicated way of creating an n-dimensional array than simply adding the element on one side. To create the n-dimensional array we would do:

Remember back to how we created the chart? If we wanted to do this for a second time, we would start with the first column of our data, which is the ID of the chart in our dataset. Then we would loop through and check if the data in row 0 has an ID equal to “x”.

3. How do we assign a value to a variable in Python?

If X is a variable, then:

Bullet Point:4. Explain the concept of a loop in Python

Paragraph: A loop is a code block that executes repeatedly until a certain condition is fulfilled. In Python, a loop can be expressed using while and for constructs.

Bullet Point:6. Explain what a list is in PythonParagraph: A list is a container that represents a set of data, each of which has a value. The elements of a list can be accessed using index or item attributes on the dictionary. ‘index’ refers to the position of the first occurrence of the item inside the list. For example, the entry in the dictionary containing the phone number is entry(0) in the list called [phone_number, '212-555-1212']. “Item” refers to the key value of the item in the list. “last” refers to the position in the list where the item occurred.

Formerly the way a list was created was either using begin, append, or pop methods individually:

Begin: Encode a Python string into an integer Return an integer from 0 to 1

Append: Append a newline character to the current string Return the string unchanged

Pop: Remove all characters from the end of the string and return it

Bullet Point:7. Explain what the eval() Function is in Python

Paragraph: A function is a piece of code that a computer can execute to produce a result. A function can take in a bunch of arguments, and the computer will make a decision about what it thinks should happen based on the arguments it receives.

Eval: A function is evaluated by the computer based on its arguments. Specifically, what happens when you try to execute this function? Let’s pretend that you have a list of phone numbers, and you want to find the number corresponding to a specific phone. You’d input that number using a comma, and that would be the given email. It would then be added to the list, and you’d be given the result.

Executed incorrectly that result e.g. might be a number.

4. What are data types in Python?

The built-in data types that Python offers are:

• – Integer (int)
• – Float
• – String
• – List
• – Dictionary
• – Tuple
• – Boolean
• – None

We’ll explain how to create lists, dictionaries, and tuples in the next section.

A simple hello world program might look like this:

If we look at the first line, it's nothing too complicated! It has just a string, a boolean, and a separate string. That’s it. Now, this first program is purely a demonstration. It really doesn’t do anything unless you run it. We’ll save the program in a file called “hello_world.py”. We can run the program just like any other Python file:

How the hello world file is structured is mentioned at the very beginning of this article. Every line starts with a Python statement followed by a succession of statements, one after the other, each describing what behavior we want to see from the program when it’s run. Until the program is run, its contents are still a string, but we expect that if the program is run then that string will be an instance of some class we created, for example, “hello_world.py”. How we can construct this class in the first place is beyond the scope of this article. For completeness, some Python examples are shown and for each, the Python statement that is executed after the example is run.

The line containing the Python statement saying: print(“Hello World!”) will be executed at the very beginning of the script. This statement will print the contents of the hello_world.py file to the front-most screen on your Pi.

The line of statements following the print statement is called the code block. Each statement in a code block always starts with a Python statement and an object/function. The argument is passed to the function is what the function needs to get from its argument list (if there is one) to run its function.

5. How do we access the value of a variable in Python?

To access the value of a variable in Python, you must use the assignment operator, ‘=’. The assignment operator is used for assigning values. It is equal to the (=) sign.

So if you saw this prompt, you would know what follows! Let me show you how you can access various types of information about a variable. You can use this information to create a few different types of data and perform many different operations on them.

Here are some examples of what you would see if you did what I did and clicked through to the ‘var command’!

We can see data types and information about the type of default values assigned to some variables here. The types of ‘str’ and ‘bool’ would be self-explanatory and we’d also see the default value assigned to each!

Let’s take a look at what we want to do.

Below the ‘=’ box with the language we’re in, we have ‘Python’. What can we put in this box? We want to put ‘1’. How do we get the string instead of the default false? Before we look at the implementation of the string method in the str module, let’s look at the equals and hash comparisons in the following imports. The two methods below are the equals and hash codes, respectively.

If you remember from the last article about schedule_time, we only had two arguments, ‘time’ and ‘days’, so, in the case of the = operator being used in this case, ‘str(time)’ is the string representation of ‘str(days=[0,5,10,15])’. This is what the equals method looks like for the str variable:

This is where the hash comparison comes into play. If you recall, we saw a value of ~32000 in the days variable, and that ‘days’ was a dictionary with two items, ‘days’ and ‘time’.