python期货和元组拆包 [英] python futures and tuple unpacking
问题描述
什么是用愚蠢的/惯用的方法来实现诸如将元组与期货拆包之类的东西?
What is an elagant/idiomatic way to achieve something like tuple unpacking with futures?
我有类似的代码
a, b, c = f(x)
y = g(a, b)
z = h(y, c)
，我想将其转换为使用期货.理想情况下，我想写一些类似的东西
and I would like to convert it to use futures. Ideally I would like to write something like
a, b, c = ex.submit(f, x)
y = ex.submit(g, a, b)
z = ex.submit(h, y, c)
该行的第一行
TypeError: 'Future' object is not iterable
虽然.如何获得 a，b，c 而不必进行3个其他的 ex.submit 调用?IE.我想避免这样写:
though.
How can I get a,b,c without having to make 3 additional ex.submit calls? ie. I would like to avoid having to write this as:
import operator as op
fut = ex.submit(f, x)
a = client.submit(op.getitem, fut, 0)
b = client.submit(op.getitem, fut, i)
c = client.submit(op.getitem, fut, 2)
y = ex.submit(g, a, b)
z = ex.submit(h, y, c)
我猜可能的解决方案是编写一个如下所示的 unpack 函数，
import operator as op
def unpack(fut, n):
return [client.submit(op.getitem, fut, i) for i in range(n)]
a, b, c = unpack(ex.submit(f, x), 3)
y = ex.submit(g, a, b)
z = ex.submit(h, y, c)
有效:例如，如果您首先定义:
which works: for example if you first define:
def f(x):
return range(x, x+3)
x = 5
g = op.add
h = op.mul
那么你就得到
z.result() #===> 77
我认为类似的东西可能已经存在.
I thought something like this might already exist.
以上内容仅适用于 dask.distributed.Future .它不适用于普通的 concurrent.futures.Future .
The above only works with dask.distributed.Future. It does not work for plain concurrent.futures.Future.
推荐答案
快速浏览:
https://docs.python.org/3/library/concurrent.futures.html#concurrent.futures.Future
建议您必须做类似的事情
suggests that you'll have to do something like
afuture = ex.submit(f, x)
a,b,c = afuture.result()
...
submit 返回一个 Future 对象，而不是运行 f(x)的结果.
submit returns a Future object, not the result of running f(x).
这个SO答案表明，链接期货并非无关紧要:
This SO answer indicates that chaining futures is not trivial:
