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Python List (With Examples)

Arrays, by contrast, assume the same type of components. The lists do not have too strict restrictions, limits regarding size indicators. Due to the features under consideration, lists turn into a fairly flexible tool that allows you to conveniently work with data in Python.

Python List code

The process of formation and subsequent filling of the structure

Before you can use the list, you should initialize it. How does this happen? In most cases, a number of available methods are envisaged. Here is an example where you can see the definition of an empty list, which is called data. In the future, it is displayed directly on the screen:

>>> data = []
>>> data

[]

How is it possible to place elements of interest to the programmer in a new list? This is done directly when you create the list. To do this, simply create an enumeration by resorting to square brackets. Here's what it looks like in practice:

>>> data = [5, 'a', ['python'], 20]
>>> data
[5, 'a', ['python'], 20]

To fill out the lists, they resort to the use of various kinds of literals. Suppose strings are applied, as demonstrated in the following example:

>>> data = list('python')
>>> data
['p', 'y', 't', 'h', 'o', 'n']

In aggregate, for various kinds of objects are filled in accordance with automatic algorithms. To ensure this, you should use list generators. Such mechanisms make it possible to reach a certain expression in relation to each component of a given sequence of points.

Adding components and list items

 

In the case when you need not only to form a list, but also to enter new data into it, it increases automatically. The number of cells is added exactly the one that is needed at the moment. To add an item to the list, there is a special method that allows you to do so. It takes as an argument exactly the object to be added. The result? The element is at the very end. Let's look at an example:

>>> data = list('python')
>>> data
['p', 'y', 't', 'h', 'o', 'n']

If necessary, you can place each of the specified objects elsewhere in the list. To do this, you should resort to a given index. A method called insert by programmers can help with the implementation of this task. If the list already exists, you must call it by passing in an object and its number as the desired argument. Here's what it looks like in practice:

>>> data = list('ython')
>>> data.insert(0, 'p')
>>> data
['p', 'y', 't', 'h', 'o', 'n']

Importantly! List objects are numbered starting from the zero position.

Ability to expand the list

 

In the event that you have to work with different sets of data that need to be merged later, use the extend method. It is called on any of these objects and the second object is written as an argument. Thus, their connection into a single whole is ensured. It looks like this:

>>> data1 = list('pyt')
>>> data2 = list('hon')
>>> data1.extend(data2)
>>> data1
['p', 'y', 't', 'h', 'o', 'n']

It turns out that the components 2 of the list are automatically rewritten to the final area 1.

How can I remove a list component?

 

Thanks to the built-in functions available in this language, you can add new data, as well as delete it if necessary. To get rid of any component of the list, you should use the remove and pop functions. The first causes the list object to be deleted with the selected value. It comes first on the index.

>>> data = list('pytthon')
>>> data.remove('t')
>>> data
['p', 'y', 't', 'h', 'o', 'n']

The second method has a slightly different version of the impact. You can use it to retrieve a list component, regardless of its index. Let's show how this happens with the following example

>>> data = list('pytthonn')
>>> data.pop(3)
't'
>>> data.pop()
'n'
>>> data
['p', 'y', 't', 'h', 'o', 'n']

If the number of the required object does not need to be transmitted, the latter will be deleted later.

Manipulating the clearing of the list

 

You can quickly get rid of list items using a function called Clear. It is called by creating an object previously created, the same as in the following example:

>>> data = list('python')
>>> data.clear()
>>> data

[]

Importantly! The list itself will not be deleted after you perform this operation.

Learning to get the size

By using a built-in method that uses the name len, you can indicate the number of items in the Python list. In this case, we mean its length. With this function, you can determine the total number of available list members.

>>> data = list('python')
>>> len(data)
6

You can also see how many selected objects are available. In this case, the Count method helps. Call it for the currently used list. The role of arguments here is played by the initial component:

>>> data = list('python')
>>> data.count('p')
1

Fact! This function is very useful, because with its help you can search for literals, in addition, it shows any kind of links to objects of interest.

Item sorting process

 

For the list, this is important. Sorting is done through the sort function. What is this indicator responsible for? There is a process of ordering here. It concerns the elements that are currently present in the list selected by the programmer. At the same time, an important indicator is that the optimal way of sorting is selected, this is done automatically:

>>> data = list('python')
>>> data.sort()
>>> data
['h', 'n', 'o', 'p', 't', 'y']

Suppose, using the above method, it is possible to change the arrangement of numbers, which is taking place at the moment. The same goes for strings, characters. You can sort them as it is convenient. for example, you can put them alphabetically or ascending.

Is a coup possible?

 

Practice shows that sometimes you have to put the components of the list in the opposite order. Such a need may arise after the standard sorting. There is a special function that allows you to implement this and it is called reverse.

>>> data = list('python')
>>> data.reverse()
>>> data
['n', 'o', 'h', 't', 'y', 'p']

As you can see, the main function of this object is to change the order of the elements to the opposite of the original.

Implementation of encoding

 

If you plan to get lists that are the same for a standard and a familiar operation, assignment is not sufficient. If there are a total of 2 lists, you can use the copy function. The fact is that the desired object in this case is not copied. Only 1 link to it is generated.

>>> data1 = list('python')
>>> data2 = data1.copy()
>>> data2
['p', 'y', 't', 'h', 'o', 'n']

If you use this method, a similar list is created in the existing list. This is done automatically. This process concerns the internal content of the object of interest. It can then be assigned to any suitable link.

Search engine manipulation

If you want to find a particular component of the list or find the index of an item that is known to you, you can resort to a function called index. What is the argument in this case? Such a role is tried on by a literal or the object of interest initially.

>>> data = list('python')
>>> data.index('o')
4

So, you can make sure that you can get the index of the item displayed on the monitor screen, after all the manipulations you have done.

How do I convert a string to a list?

 

The list includes a whole list of characters. It can be converted. As a result, it gets a representation in the form of strings. To achieve this task, the newly designated string is concatenated, and then returned to it the value characteristic of the Join function. This method assumes an argument whose role is performed by the list. Consider a specific example where a list string receives a transformation:

>>> data = list('python')
>>> str = ".join(data)
>>> str
'python'

A row designated in this way can receive any list items and their value at a time.

Two-dimensional list: how to get it?

 

Standard platform capabilities make it possible to interact with a two-dimensional view. This applies to the list of certain values in the software. How can this be realized? The assignment operator usually comes to the rescue. Just add it to the list. That way, you get a two-dimensional list effortlessly. It has the following appearance:

>>> data = [[1, 2, 8], [2, 5, 6]]
>>> a[0]
[1, 2, 8]
>>> a[1]
[2, 5, 6]

What does the above combination show? Here it is clearly seen that the construction of a two-dimensional list occurs when several one-dimensional ones are used.

Convert to a dictionary list

 

The dictionary has special properties. It's no secret that he is able to keep a given collection of certain objects. To gain unhindered access to them, you must have an access key. There is an items method. It is he who allows you to convert the dictionary available to us at the moment into a list. We can show this with an example:

>>> dic = {}
>>> dic['name'] = 'John'
>>> dic['age'] = 25
>>> data = dic.items()
>>> data
dict_items([('name', 'John'), ('age', 25)])

If you look at the list that was presented in this way, you can see the pairs with the keys that are assigned certain values.

Summing up

 

As standard, the Python library provides many useful features. They allow you to interact with lists without any problems, so that any employee or programmer can manipulate a particular set of data. You can do this automatically, changing the lists of any list to certain items, as well as convert them, providing other options for presenting information data.

 

There is a whole list of functions and methods by which you can work with lists. They can add items to the end area of the list, add items to the list, delete items on first occurrence or generate exceptions, and delete any list items, including all without exception.