python-多重处理：同时追加到2个列表

我有以下代码：

from multiprocessing import Pool, Manager
import numpy as np

l = Manager().list()

def f(args):
    a, b = args
    l.append((a, b))


data = [(1,2), (3,4), (5,6)]
with Pool() as p:
    p.map(f, data)
x, y = np.transpose(l)

# do something with x and y...

实际上,数据是具有很多值的数组,转置操作很长,而且占用内存.

我想将“ a”和“ b”直接附加到列表x和y上,以避免转置操作.重要的是,输出必须保持数据中的对应关系并看起来像这样：[[1,3,5],[2,4,6]

有什么聪明的办法做到这一点？

解决方法:

您可以使函数返回值并将其附加到主进程中,而不必尝试从子进程中附加.您无需关心子流程之间的相互访问(也无需使用管理器).

from multiprocessing import Pool


def f(args):
    a, b = args
    # do something with a and b
    return a, b


if __name__ == '__main__':
    data = [(1,2), (3,4), (5,6)]
    x, y = [], []
    with Pool() as p:
        for a, b in p.map(f, data):   # or   imap()
            x.append(a)
            y.append(b)

    # do something with x and y
    assert x == [1,3,5]
    assert y == [2,4,6]

标签：multiprocessing,shared-memory,python
来源： https://codeday.me/bug/20191025/1932095.html