Here it's a useless example, but it's handy when you know your function will return a huge set of values that you will only need to read once. > print(mygenerator) # mygenerator is an object! > mygenerator = create_generator() # create a generator Yield is a keyword that is used like return, except the function will return a generator. BUT, you cannot perform for i in mygenerator a second time since generators can only be used once: they calculate 0, then forget about it and calculate 1, and end calculating 4, one by one.
It is just the same except you used () instead of. Generators do not store all the values in memory, they generate the values on the fly: > mygenerator = (x*x for x in range(3)) Generators are iterators, a kind of iterable you can only iterate over once. These iterables are handy because you can read them as much as you wish, but you store all the values in memory and this is not always what you want when you have a lot of values. in." on is an iterable lists, strings, files. When you use a list comprehension, you create a list, and so an iterable: > mylist = Įverything you can use " for. Reading its items one by one is called iteration: > mylist = When you create a list, you can read its items one by one. And before you can understand generators, you must understand iterables. To understand what yield does, you must understand what generators are. This is the link to the complete source: Module mspace. This piece of code was written by Jochen Schulz (jrschulz), who made a great Python library for metric spaces. Is a list returned? A single element? Is it called again? When will subsequent calls stop?ġ. What happens when the method _get_child_candidates is called? If self._leftchild and distance - max_dist = self._median:Īnd this is the caller: result, candidates =, Ĭandidates.extend(node._get_child_candidates(distance, min_dist, max_dist)) What is the use of the yield keyword in Python? What does it do?įor example, I'm trying to understand this code 1: def _get_child_candidates(self, distance, min_dist, max_dist): Answers without enough detail may be edited or deleted. Want to improve this post? Provide detailed answers to this question, including citations and an explanation of why your answer is correct.
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