如何在Ruby中有效地串联多个数组? [英] How to efficiently concatenate multiple arrays in Ruby?

问题描述

我只想在Ruby中连接多个数组，却找不到令人满意的方法.

I just wanted to concatenate multiple arrays in Ruby and couldn't find a satisfying way to do so.

示例输入:

foo = [1, 2, 3]
bar = [4, 5, 6]
baz = [7, 8, 9]

预期结果:(无需修改现有阵列)

Expected result: (without modifying the existing arrays)

[1, 2, 3, 4, 5, 6, 7, 8, 9]

我的实际数组大了 ，所以我对有效的解决方案感兴趣.可能还会有三个以上的数组，因此首选短语法.

My actual arrays are much larger, so I'm interested in an efficient solution. There may also be more than three arrays, so a short syntax is preferred.

• foo + bar + baz是显而易见的，它简洁明了.但是它被评估为(foo + bar) + baz.换句话说:它创建一个中间数组[1, 2, 3, 4, 5, 6]，该中间数组在整个操作后将被丢弃.如文档中所述:

• foo + bar + baz is the obvious one, it's concise and clear. But it is evaluated as (foo + bar) + baz. In other words: it creates an intermediate array [1, 2, 3, 4, 5, 6] that is thrown away after the whole operation. As noted in the documentation:

在数组上重复使用+=可能效率很低

[*foo, *bar, *baz]基本上内联元素，这对于大型数组也不是很有效.在我看来，这更像是一种黑客.

[*foo, *bar, *baz] basically inlines the elements which is not very efficient for large arrays, either. It also looks more like a hack to me.

[foo, bar, baz].flatten(1)似乎比上述情况还要糟糕.

[foo, bar, baz].flatten(1) seems to be even worse than the above, performance wise.

[].concat(foo).concat(bar).concat(baz)是最快的，但看起来很麻烦，并且需要多次方法调用.

[].concat(foo).concat(bar).concat(baz) is the fastest, but it looks cumbersome and it needs multiple method invocations.

对于这样的基本任务，应该没有简单的类方法吗?像这样:

Shouldn't there be a simple class method for such a basic task? Something like:

Array.concat(foo, bar, baz)

我缺少明显的东西吗?

推荐答案

如果您已经确定多重连接是最快的方法，则可以使用reduce更好地编写它:

If you've already determined that multiple concatenation is the fastest method, you can write it nicer using reduce:

[foo, bar, baz].reduce([], :concat)

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