yield

I'm new to Scala, and from what I understand yield in Scala is not like yield in C#, it is more like select. Does Scala have something similar to C#'s yield? C#'s yield is great because it makes writing iterators very easy. Update: here's a pseudo code example from C# I'd like to be able to implement in Scala: public class Graph<T> { public IEnumerable<T> BreadthFirstIterator() { List<T> currentLevel = new List<T>(); currentLevel.add(_root); while ( currentLevel.count > 0 ) { List<T> nextLevel = new List<T>(); foreach( var node in currentLevel ) { yield return node; nextLevel.addRange( node

一丶yield关键字 yield的英文单词意思是生产，在函数中但凡出现yield关键字，再调用函数，就不会继续执行函数体代码，而是会返回一个值。 def func(): print(1) yield print(2) yield g = func() print(g) <generator object func at 0x10ddb6b48> 生成器的本质就是迭代器，同时也并不仅仅是迭代器，不过迭代器之外的用途实在是不多，所以我们可以大声地说：生成器提供了非常方便的自定义迭代器的途径。并且从Python 2.5+开始，[PEP 342：通过增强生成器实现协同程序]的实现为生成器加入了更多的特性，这意味着生成器还可以完成更多的工作。这部分我们会在稍后的部分介绍。 def func(): print('from func 1') yield 'a' print('from func 2') yield 'b' g = func() print(F"g.__iter__ == g: {g.__iter__() == g}") res1 = g.__next__() print(f"res1: {res1}") res2 = next(g) print(f"res2: {res2}") # next(g) # StopIteration g.__iter__ == g: True

I know that yield turns a function into a generator, but what is the return value of the yield expression itself? For example: def whizbang(): for i in range(10): x = yield i What is the value of variable x as this function executes? I've read the Python documentation: http://docs.python.org/reference/simple_stmts.html#grammar-token-yield_stmt and there seems to be no mention of the value of the yield expression itself. You can also send values to generators. If no value is sent then x is None , otherwise x takes on the sent value. Here is some info: http://docs.python.org/whatsnew/2.5.html

Is there any way to mix recursion and the yield statement? For instance, a infinite number generator (using recursion) would be something like: def infinity(start): yield start # recursion here ... >>> it = infinity(1) >>> next(it) 1 >>> next(it) 2 I tried: def infinity(start): yield start infinity(start + 1) and def infinity(start): yield start yield infinity(start + 1) But none of them did what I want, the first one stopped after it yielded start and the second one yielded start , then the generator and then stopped. NOTE: Please, I know you can do this using a while-loop: def infinity(start

send与next def generator(): print(123) count = yield 1 print('=====',count) print(456) yield 2 g = generator() ret = g.__next__() print('****',ret) ret = g.send('套你大象')#send的效果与next一样 print('***',ret) View Code send在获取下一个值时，会在上一个yield值之后传一个值进来 send获取下一个值的效果和next效果基本一致 只是在获取下个值的时候，就给上一个值的位置传递一个数据。 send的注意事项 　1.　第一次使用生成器的时候，必须使用next获取下一个值。 　2. 最后一个yield不能接收外部的值 来源： https://www.cnblogs.com/zly9527/p/11370721.html

yield —> 生成器 是什么？ 生成器是一个不断产生值得函数 包含yield语句得函数是一个生成器 生成器每产生一个值（yield语句），函数就会被冻结，被唤醒后再产生一个值 e.g. def gen ( n ) : for i in range ( n ) : yield i ** 2 输出结果为： 0 1 4 9 16 为啥要用生成器？ 生成器相比一次列出所有内容的优势 更节省存储空间 响应更迅速 使用更灵活 永远只需要一个元素的存储空间 来源： https://blog.csdn.net/qq_44790423/article/details/99694801