这段代码在 Python 里能怎么改写成效率更高的吗，听说 for 循环比较慢

[zxCoder]

    xs = []
    ys = []
    zs = []
    for data in ls:
        _x, _y, _z = data
        xs.append(_x)
        ys.append(_y)
        zs.append(_z)

[niubee1]

@NoAnyLove 我测了一下，zip 稍快一些

[niubee1]

blob:https://imgur.com/0782fae0-e12e-46fe-a6ea-0db5e1e39c72

[niubee1]

[NoAnyLove]

@niubee1 同意，你的版本更快，

In [101]: def t1(ls):
...: flat = list(itertools.chain.from_iterable(ls))
...: xs = flat[::3]
...: ys = flat[1::3]
...: zs = flat[2::3]
...: return xs, ys, zs
...:

In [102]: def t2(ls):
...: xs, ys, zs =list(zip(*ls))
...: return list(xs), list(ys), list(zs)

In [113]: ls=[[i, i+1, i+2] for i in range(1, 98, 3)]

In [114]: %timeit t1(ls)
4.26 µs ± 17.3 ns per loop (mean ± std. dev. of 7 runs, 100000 loops each)

In [115]: %timeit t2(ls)
3.2 µs ± 19.1 ns per loop (mean ± std. dev. of 7 runs, 100000 loops each)

[niubee1]

其实省掉 extend 过程，直接返回数组的话，还能再提高点性能

[niubee1]

@NoAnyLove 🤝 其实大家思路都差不多，python 要提高效率的话，应该尽可能的使用内置函数

[NoAnyLove]

@niubee1 对，就是这个道理，内置函数底层执行更快 🤝

[shyrock]

@niubee1 #19 学习了。

[wuwukai007]

#19 楼 一行代码开启新世界

[princelai]

```python
def func4(ls):
xs = list(islice(chain.from_iterable(ls), 0, None, 3))
ys = list(islice(chain.from_iterable(ls), 1, None, 3))
zs = list(islice(chain.from_iterable(ls), 2, None, 3))


def func5(ls):
xs = list(compress(chain.from_iterable(ls), cycle([1, 0, 0])))
ys = list(compress(chain.from_iterable(ls), cycle([0, 1, 0])))
zs = list(compress(chain.from_iterable(ls), cycle([0, 0, 1])))
```
itertools 里的内置函数速度都还可以

[rationa1cuzz]

@niubee1 ls[::] 是干嘛？我怎么看不懂啊，求教，另外为什么我测的是列表推导式更快一点，数量级越大越明显

[rationa1cuzz]

@niubee1 另外，只有在 data=[(x,y,z),(x2,y2,z2,...)] 为元祖 zip 才会有明显速度优势,
data[(x,y,z),(x2,y2,z2,...)] range(100000)
for： spend_time:0.03163599967956543
列表推导式：spend_time:0.012620925903320312
zip： spend_time:0.0060007572174072266

data[(x,y,z),(x2,y2,z2,...)] range(100000)
for： spend_time:0.03195595741271973
列表推导式：spend_time:0.012039899826049805
zip： spend_time:0.016546964645385742

[htaoreg]

xs, ys, zs = zip(*ls)