In-depth study of python yield, generator, and pythonyield
PrefaceIt is hard to say that you will do things you have never used and that you have never understood. Although I have been familiar with the concept of python coroutine before, I am just taking a look at it. During a conversation these two days, when someone asks about the coroutine, I can't remember what I 've seen, later, I suddenly thought of yield, but it was too late. I can only say th
Simple generators have many advantages. In addition to being able to express the process of a class of problems in a more natural way, the generator greatly improves many inefficiencies. In Python, function calls are expensive; In addition to other factors, it takes some time to resolve the list of function arguments (in addition to other things, analyze positional and default parameters). Initialization of the frame object also takes some steps to bu
PHP5.5 introduces the concept of an iterative generator, the concept of iteration is already in PHP, but the iterative generator is a new feature of PHP, similar to the iterative generator in Python3, to see how the PHP5.5 Iteration Builder is defined.
function xrange ($start, $end, $step = 1) {for ($i = $start; $i Yield $i;}}foreach (xrange (1, 1000000) as $num
an object to get the next elementCustom iteratorsOnce you understand the iterator protocol, you can customize the iterator.The following example implements a myrange type, which implements the __iter__ () method, which returns the object itself as an iterator object, and implements the next () method to get the next element in the container, when there is no accessible element. Throws a Stopiteration exception. classMyRange (object):def __init__(self, N): Self.idx=0 SELF.N=Ndef __iter__(self
This article mainly introduces enhanced generator in Python, namely coroutine related content, including basic syntax, usage scenarios, considerations, and similarities and differences with other language implementation.Enhanced generatorThe usage scenarios and ideas of yield and generator are described above, and only the next method of generator is used, in fac
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I. What are the conditions for Parallel Running of generator sets?
The whole process of putting the generator set into parallel operation is called parallel operation. Run one generator set first and send the voltage to the bus. After the other generator set is started, it should be in
The builder is an advanced usage in Python, and for some time I struggled to understand the generator until I saw the phrase "theyield statement suspends the state of the generator function, retains enough information so that it can continue from where it left off ," and it dawned on me This is the state in the generator hangs, this sentence reminds me of when I
Because the Send method is the key to the implementation of the coprocessor, it is necessary to learn the next send method in detail, because it is really weird; official documentation generator::send (PHP 5 >= 5.5.0, PHP 7) Generator::send-send a value to the generator Description public mixed generator::send (mixed $
This article mainly introduces the Python generator definition and simple usage, combined with the example form more detailed analysis of the Python generator concept, principles, usage and related operations considerations, the need for friends can refer to the following
The examples in this article describe Python builder definitions and simple usages. Share to everyone for your reference, as follows:
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Before you can learn the builder, you must understand the iterator first. Because the generator is a special kind of iterator , and the generator is more elegant.
An explanation of the iterator can refer to my other blog post: www.cnblogs.com/chichung/p/9537969.html
Let's start with a relatively simple generator, and slowly realize w
This article introduces the content is about PHP Generator generator Understanding, has a certain reference value, now share to everyone, the need for friends can refer to
Reprinted and collated from: Send where, snow, the Corner, PHP HandbookGenerator (Generator)
Issues that can be solved
Quoted from official website: The
This article introduces to you about the performance of PHP in the optimization of the weapon: PHP generator of the detailed, there is a certain reference value, the need for friends can refer to, I hope you have some help.
If you are a small partner in Python or other languages, you should not be unfamiliar with generators. However, many PHP developers may not know the generator, perhaps because the
In Python, all collections can be iterated, and within the Python language, iterators are used to supportFor loopBuilding and extending collection typesTraverse a text file line by rowList derivation, dictionary derivation, and set derivationTuple unpackingWhen calling a function, use the * unpacking argumentTopics covered in this chapterLanguage internal use of ITER (...) built-in functions to manipulate the way an object can be iteratedHow to implement the classic iterator pattern using Python
This article mainly introduces Generator and yield in Python. This article describes list derivation and Generator expressions, Fibonacci series, Generator, coroutine and yield expressions, and Generator and coroutine usage, for more information, see
List derivation and generator
The generator (generator) is the new data type introduced by the ES6 standard. A generator looks like a function, but can be returned multiple times.ES6 define the generator standard Buddy borrowed from the Python generator concept and syntax, if you are familiar with Python
First, the basic conceptThe generator function is a function that can pause execution, return a iterator object, yield is a paused identityfunction* gen () { 1; 2; }The generator function has a *, with a yield statement inside it.function* gen () { 1; 2; return ' 1 '= Gen ();//Call the generator function to return the iterator object Console.lo
This article introduces the python iterator and generator in detail. 1. what is an iterator?
Let's talk about iteration first. iteration is a process that repeats many times, for example, for loop.
The for loop can iterate on all objects with iter methods. what is the iter method?
Whether an object can be iterated depends on whether the object has an iter method. when the object's iter method is called, an iterator is returned. this iterator must hav
The generator function is the first available feature in python2.2. It is built in Version 2.3 to support this feature, and yield becomes a keyword, the generator is enhanced in later versions (for example, exception handling is added ). Similar features (iterators) are introduced in C #2.0, which have many similarities. This article discusses ironpython 2.0 beta3.
Any function that contains the yield exp
:
>>> [x * x for x in range(1, 11) if x % 2 == 0][4, 16, 36, 64, 100]
小结:The use of list generation, can be generated quickly list , can be deduced from one list another list , and the code is very concise.
2. Generator
???? With list generation, we can create a list directly. However, with memory limitations, the list capacity is certainly limited. Also, creating a list of 1 million elements takes up a lot of storage space, and
Get started and transition to PHP7 -- lightweight "set" iterator-Generator lightweight "set" iterator-Generator
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Generator is a new language feature added to PHP 5.5. However, it does not seem to be widely used by many PHP developers. Therefore, before learning about the improvements made by PHP 7 to Gener
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