Generators can’t be rewound. You have the following options: Run the generator function again, restarting the generation: y = FunctionWithYield() for x in y: print(x) y = FunctionWithYield() for x in y: print(x) Store the generator results in a data structure on memory or disk which you can iterate over again: y = list(FunctionWithYield()) for … Read more
Let’s get one thing out of the way first. The explanation that yield from g is equivalent to for v in g: yield v does not even begin to do justice to what yield from is all about. Because, let’s face it, if all yield from does is expand the for loop, then it does … Read more
I think the accepted answer is great, but it seems many people have failed to grasp some fundamental points. First, Scala’s for comprehensions are equivalent to Haskell’s do notation, and it is nothing more than a syntactic sugar for composition of multiple monadic operations. As this statement will most likely not help anyone who needs … Read more
The yield contextual keyword actually does quite a lot here. The function returns an object that implements the IEnumerable<object> interface. If a calling function starts foreaching over this object, the function is called again until it “yields”. This is syntactic sugar introduced in C# 2.0. In earlier versions you had to create your own IEnumerable … Read more
To understand what yield does, you must understand what generators are. And before you can understand generators, you must understand iterables. Iterables When you create a list, you can read its items one by one. Reading its items one by one is called iteration: >>> mylist = [1, 2, 3] >>> for i in mylist: … Read more