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Python List Generator

And even if we take into account the fact that in some situations it is possible to do without the so-called generators, through their use it is possible to simplify the procedure for working with rather complex algorithms several times.

Features of the implementation of simple generation

If we consider the simplest and easiest way by which you can create lists, then this should include the usual process of assigning it the necessary objects or values. If the objects that will make up a certain sequence are few enough, then in this case they can be alternately simply listed.

But if their number goes beyond the boundaries of 10, then in this case it is worth thinking about using a list generator, as this will make it possible to significantly simplify the process of creating an algorithm and a program in the future. Through the application of this design, the implementation of such a process as automatic filling will be ensured. This will be implemented according to certain instructions.

In the following example, you can understand how the process of creating a list of numbers in Python works through the use of a generator. The variable i will be a reference to a specific element taken from the data object. If you pay attention to the range function, then it will be responsible for several arguments at the same time. With their help, the process of establishing specific boundaries for the sequence of numbers that will be generated will take place. Using the print method, you can display information on the screen:

Python List Generator

It is worth paying attention to the fact that in Python, list generators can work not only with numerical values. In the following example, you can see that the generator can carry out the process of passing a whole line or a reference to it if necessary:

Python List Generator

In the event that this part of the program is executed, a list of characters that were part of a particular specified string will be created. If we draw an analogy with the example with numbers, which was placed above, then the same print method is used to display it on the screen.

Features of using the generator with the condition

Among the sufficiently applied options for generating lists is a generator with a condition. If we draw an analogy with the options listed above, then such methods can be considered rather trivial in terms of filling the list with symbols or numerical values.

If you look at the generator with a condition, then it acts as a design that makes it possible to set certain conditions for performing a specific task. Here you can consider such an example: you need to transfer from the sample to the list only those numeric values that are even:

Python List Generator

At this stage, a command such as if is mandatory. After it, there is a mandatory instruction that indicates that each element has a condition that it must necessarily fulfill. In the presented example, the process of returning zero occurs if the procedure for calculating the balance of division by an integer occurs. Those figures that pass the test will be included in the list.

Features of using a generator with a cycle

Considering the Python programming language, it is worth paying attention to the fact that it has the ability to carry out the process of generating lists through the use of loops. For initialization, they must be placed in square brackets.

In the example that will be discussed below, several for constructs will be used that will perform a process such as alternately iterating through the values used for two variables j and i. Using the range method, you should specify a numeric range that will be from 0 to 3:

Python List Generator

In the process of executing the presented code fragment, a list will be created using the generator based on the multiplication of variables such as j and i in turn. This allows you to generate a list as a result, which will consist of 9 elements.

Features of nested list generation

Very often, a programmer is faced with a task in which he needs to use lists in which several dimensions are used. For example, in the process of working with such an element as mathematical matrices, there is a need to use multidimensional datasets.

To implement this in the Python programming language, generators are also used for this, while a loop will be placed inside one list to create another. The square brackets are scope constraints, as can be found below:

Python List Generator

Considering the presented code, you can see that in the process of its implementation there is such a process as the creation of a two-dimensional array, the dimension of which is 3x3 through the use of two-dimensional arrays in Python generators. The main elements here are the numerical values that will be selected through the use of the range method, as in the options listed above.

All the variables that are used here will gradually increase by one, and then multiply with each other. In order to implement a visual display of the list that was generated, the print command is also used.

Very often, a matrix of zeros can be used during the preparation of nested lists. Here you can pay attention to this example:

Python List Generator

Features of using the list generator with lambda

As practice shows, in the Python programming language, special lambda functions are very often used, which are a function through the use of which you can return a certain value.

Such a mechanism has its undeniable advantage, since it can be used within any expression. It also makes it possible to significantly reduce future program code, as this allows you not to perform additional declarations of new methods. In the lambda list generator, functions are also used quite often.

In the example below, a certain sequence of numbers will be formed, which will be formed after the range method:

Python List Generator

For example, you can see that in the process of executing the function, a list is generated, in which as a result there are elements of numbers that were raised to a square. To display data on the screen, the print function is used.

Features of using itertools

In the event that to create a list there is a need to use advanced generation, then for this you need to perform such a procedure as connecting a special library itertools. Through the use of such a library, it is possible to generate certain values by following the established rules. In order to activate this library for the presented module, you need to make the following statement at the beginning of the applied program file:

Python List Generator

Those methods that are part of the library used make it possible to carry out such a process as generating lists, but through the use of improved loops. For example, by using such a library, it is possible to create lists of numeric and symbolic values. On the example of the following code, you can get acquainted with the features of generating a list in which such a function as repeat is used:

Python List Generator

From the presented result, it can be seen that there is a process of forming a sequence of those elements that are the same, a certain number of times. In a particular example, repetition occurs exactly 5 times.