yield | 易学教程

迭代器和生成器3

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总结：生成器并行，实际上是串行的，但是时间上给人的感觉是并行的 import timedef product(name): print("%s 准备" %name) while True: try: name1 = yield #yield生产器中实现并行效果 # print("here") print("[%s]开始了，[%s]准备" %(name1,name)) except StopIteration as e: print(e.value) print("here")c = product("ripple")c.__next__()b1 = "wangzi"c.send(b1) #发送一个值作为yield的返回值c.__next__()def produces(name): c =product('A') c2 =product('B') c.__next__() c2.__next__() print("比赛开始了") for i in range(10): time.sleep(0.5) print("一共十场比赛") c.send(i) c2.send(i)produces("ripple")运行结果：来源： https://www.cnblogs.com/mygodswangzi/p/11896796.html

16 协程和www

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1、一个应用程序一般对应一个进程，一个进程一般有一个主线程，还有若干个辅助线程，线程之间是平行运行的，在线程里面可以开启协程，让程序在特定的时间内运行。 2协程和线程的区别是：协程避免了无意义的调度，由此可以提高性能，但也因此，程序员必须自己承担调度的责任，同时，协程也失去了标准线程使用多CPU的能力。什么是协程答:协程是一段在主线程中执行的代码逻辑（代码块）协程不是多线程，本质依然是从上到下依次执行。 Unity协程的执行原理（执行过程）是什么？（15分,每条5分）答：（1）unity中协程执行过程中，通过yield return XXX，将程序挂起，去执行接下来的内容。（2）注意协程不是线程，在为遇到yield return XXX语句之前，协程的方法和一般的方法是相同的，也就是程序在执行到yield return XXX语句之后，接着才会执行的是 StartCoroutine（）方法之后的程序。（3）协程走的还是单线程模式，仅仅是将yield return XXX语句之后的内容暂时挂起，等到特定的时间才执行。 unity中协程执行过程中，通过yield return XXX，将程序挂起，去执行接下来的内容，注意协程不是线程，在为遇到yield return XXX语句之前，协程的方法和一般的方法是相同的，也就是程序在执行到yield return XXX语句之后

PHP - json_encode a generator object (using yield)

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I have a very large array in PHP (5.6), generated dynamically, which I want to convert to JSON. The problem is that the array is too large that it doesn't fit in memory - I get a fatal error when I try to process it (exhausted memory). So I figured out that, using generators, the memory problem will disappear. This is the code I've tried so far (this reduced example obvisously doesn't produce the memory error): <?php function arrayGenerator()// new way using generators { for ($i = 0; $i < 100; $i++) { yield $i; } } function getArray()// old way, generating and returning the full array { $array

What is the Matlab equivalent of the yield keyword in Python?

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问题 I need to generate multiple results but one at a time, as opposed to everything at once in an array. How do I do that in Matlab with a generator like syntax as in Python? 回答1: When executing functions that use the yield keyword, they actually return a generator. Generators are a type of iterators. While MATLAB does not provide the syntax for either, you can implement the "iterator interface" yourself. Here is an example similar to xrange function in python: classdef rangeIterator < handle

yield函数

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https://blog.csdn.net/u011318077/article/details/93749143 来源： https://www.cnblogs.com/lin-kid/p/11887534.html

Rails 3 - yield return or callback won't call in view <%= yield(:sidebar) || render('shared/sidebar') %>

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问题 I'm migrating a Website from Rails 2 (latest) to Rails 3 (beta2). Testing with Ruby 1.9.1p378 and Ruby 1.9.2dev (2010-04-05 trunk 27225) Stuck in a situation, i don't know which part will work well. Suspect yield is the problem, but don't know exactly. In my Layout Files I use the following technique quite often: app/views/layouts/application.html.erb : <%= yield(:sidebar) || render('shared/sidebar') %> For Example the partial look like: app/views/shared/_sidebar.html.erb : <p>Default sidebar

迭代器与生成器

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[ ] ```python https://www.cnblogs.com/zhangchaocoming/p/11192436.html https://www.cnblogs.com/liangmingshen/p/10970534.html 可迭代对象内置有__iter__方法的对象，例如字符串，列表，字典，元组等等都是可迭代对象迭代器对象既内置有__next__方法的对象，执行迭代器__next__方法可以不依赖索引取值又内置有__iter__方法的对象，执行迭代器__iter__方法得到的仍然是迭代器本身通过列表生成式，我们可以直接创建一个列表，但是，受到内存限制，列表容量肯定是有限的，而且创建一个包含100万个元素的列表，不仅占用很大的存储空间，如果我们仅仅需要访问前面几个元素，那后面绝大多数元素占用的空间都白白浪费了。　　所以，如果列表元素可以按照某种算法推算出来，那我们是否可以在循环的过程中不断推算出后续的元素呢？这样就不必创建完整的list，从而节省大量的空间，在Python中，这种一边循环一边计算的机制，称为生成器：generator 　　生成器是一个特殊的程序，可以被用作控制循环的迭代行为，python中生成器是迭代器的一种，使用yield返回值函数，每次调用yield会暂停，而可以使用next()函数和send()函数恢复生成器。　

Python yield vs Ruby yield

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问题 In Ruby, the yield keyword is used to yield to closures for blocks of execution. How does this keyword differ in the Python language? 回答1: In ruby , yield is a shortcut that is used to call an anonymous function. Ruby has a special syntax for passing an anonymous function to a method; the syntax is known as a block . Because the function has no name, you use the name yield to call the function: def do_stuff(val) puts "Started executing do_stuff" yield(val+3) yield(val+4) puts "Finshed

Difference between `yield from foo()` and `for x in foo(): yield x`

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问题 In Python most examples of yield from explain it with saying that yield from foo() is similar to for x in foo(): yield x On the other hand it doesn't seem to be exactly the same and there's some magic thrown in. I feel a bit uneasy about using a function that does magic that I don't understand. What do I have to know about the magic of yield from to avoid getting into a situation where the magic does something I don't expect? What advantages does the magic provide, that I should be aware of?

python中的yield通俗理解

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I、理解yield，第一步需要理解yield和return的区别 print('yield:') def _testyield(): for i in range(5): yield i*i #这里产生生成器对象,跟java对象意思相同 generator = _testyield() for i in range(5): print(next(generator)) #-----------------------------------------------------------# print('return:') def _return(n): # 这里res是一个list[],得出的结果是[1,2,3,4,5] res = [i*i for i in range(n)] return res for i in _return(5): print(i) 上面yield和return生成的结果相同：但是这里面的区别在于： return返回的是一个list列表，而yield每次调用只返回一个数值，毫无疑问，使用return空间开销比较大，尤其是操作巨量数据的时候，操作一个大列表时间开销也会得不偿失 II、yield执行方式 def foo(): print("starting...") while True: res = yield 4 print("res:",res)