如何在Lua中对数字表求和? [英] How to sum a table of numbers in Lua?

问题描述

Lua有内置的sum()功能吗?我似乎找不到一个，而且我在文档中几乎遍历了所有地方.也许table.sum()或类似的东西可以遵循当前的惯例.但是由于找不到，所以我不得不实现它:

Does Lua have a builtin sum() function? I can't seem to find one, and I've looked almost everywhere in the documentation. Maybe table.sum(), or something of the like, to follow the current conventions. But since I couldn't find it, I had to implement it:

function sum(t)
    local sum = 0
    for k,v in pairs(t) do
        sum = sum + v
    end

    return sum
end

不过，必须实现这种简单的操作似乎有点可笑.内置功能是否存在?

It seems kind of funny to have to implement something this simple, though. Does a builtin function exist, or no?

推荐答案

我不同意，在标准库中具有原始且特定于table.sum的内容将是多余的.

I disagree, it would be redundant to have something that primitive and specific as table.sum in the standard library.

按照以下方式实现table.reduce会更有用:

It'd be more useful to implement table.reduce along the lines of:

table.reduce = function (list, fn) 
    local acc
    for k, v in ipairs(list) do
        if 1 == k then
            acc = v
        else
            acc = fn(acc, v)
        end 
    end 
    return acc 
end

并使用一个简单的lambda来使用它:

And use it with a simple lambda:

table.reduce(
    {1, 2, 3},
    function (a, b)
        return a + b
    end
)

reduce的示例实现缺少类型检查，但您应该了解一下.

The example implementation of reduce lacks type-checking but you should get the idea.

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