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Questions tagged [yield-from]

"yield from" is an expression in Python for delegating to a subgenerator.

The expression yield from was added in Python-3.3 based on PEP 380: Syntax for Delegating to a Subgenerator.

In the simplest case it can be used as a shorthand for iterating over a subgenerator, i.e.

for item in sth:
    yield item

can be replaced with:

yield from sth
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Recursing python dictionaries with yield from to generate list of nested dictionary keys

I want to generate a list of unique nested keys for each value in a dictionary such that: input_dict = {"a": {"b": "c", "d": {"e": "f"}}, "f": "g"} expected_result = [["a", "b"], ["a", "d", "e"], ["f"]] I thought something along these lines would…
wab
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How to use os.scandir() to also get back empty and non-empty directory names

In https://stackoverflow.com/a/33135143 the solution for returning recursively all file names in a directory structure looks like depicted below. I need also the information about each sub directory in the directory structure and the full path name…
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Why does this recursive ```yield from``` function not raise an error?

def prefixes(s): if s: yield from prefixes(s[:-1]) yield s t = prefixes('both') next(t) The next(t) returns 'b'. I'm just confused as to why this is because if we follow down the yield from statement, we will eventually end at…
WeyX
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`send`ing into `zip`ped generators with `yield from`

I am using Python 3.6 where you can nicely zip individual generators of one kind to get a multidimensional generator of the same kind. Take the following example, where get_random_sequence is a generator that yields an infinite random number…
wehnsdaefflae
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Is it possible to write arbitrary depth delegated generators in Python?

I would like to write a class with the following interface. class Automaton: """ A simple automaton class """ def iterate(self, something): """ yield something and expects some result in return """ print("Yielding",…
Leitram
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Any alternatives for using "yield from" inside a by-reference generator?

I want to use some methods which use Generators as their return type and by-reference. However, the problem is that a method gets another method's return value, that is returned by-reference and is a Generator, and returns it by-reference. Plus,…
MAChitgarha
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'yield from' inside async function Python 3.6.5 aiohttp

SyntaxError: 'yield from' inside async function async def handle(request): for m in (yield from request.post()): print(m) return web.Response() Used python3.5 before, found pep525, install python3.6.5 and still receive this error.
TheUnity
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`yield` throughout parsing in flask

First, I use flask. Second, I yield values like the code below. def upload_file(): if request.method == 'POST': f = request.files['file'] def generate(): yield '
'
            yield "Processing...\n"
           …
netdigger
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Breaking into the iteration process of os.walk()

My goal is to store all files and directories in a structured data tree, where each: directory is a node file is a leaf My code below works fine. However, I only take one step at a time and interrupt/restart the walking process for every…
NewNewton
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simpy using yield inside callback

I am trying to append callbacks to various events in a SimPy simulation, and I am finding that you can't use the yield keyword inside a callback. Is there a way to correctly do this, or do you have to only use callbacks within callbacks? For…
Allen Wang
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How do I get the result of a yield from in Python 2

I've got code that looks somewhat like: @asyncio.coroutine def myfunction(): result = yield from bot.whois(something) # returns an asyncio.Future() return result['account'] How would I convert this to something that works in Python 2.7? Is…
Thom Wiggers
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Why does this Python program using yield from not work?

I started with the following base code that works (Like the sample code at http://aaugustin.github.io/websockets/): import asyncio import websockets @asyncio.coroutine def servePlayer(websocket, path): yield from websocket.send("Hello…
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What happens if I do not yield anything to `yield from`?

What happens if I do not yield anything to yield from? This is an example: def inner(x): if x > 0: yield "Greater than zero" elif x==0: yield "Zero" def outer(): yield from inner(x) In this case inner(x) yields…
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strange result from yield from in python

I have a depth-first search example code in python as below. def DFS_paths_recursive(self, start, end, path = None): if path == None: path = [start] if start == end: yield path else: unvisited =…
Sissi
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