Lua:仅在表中尚未添加或删除重复项时，最明智的添加方式 [英] Lua: Smartest way to add to table only if not already in table, or remove duplicates

问题描述

我有一个字符串表.我想要一种简单的方法来删除表中的所有重复项.

I have a table of strings. I'd like an easy way to remove all of the duplicates of the table.

因此，如果表为{a, b, c, c, d, e, e}，则此操作后为{a, b, c, d, e}

So if the table is {a, b, c, c, d, e, e} , after this operation it would be {a, b, c, d, e}

或者，也许最好是，有一种方法可以将元素添加到表中，但前提是该元素尚未包含在表中.

Alternatively, and probably preferably, is there a way to add an element to a table, but only if it is not already contained within the table.

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推荐答案

为此，我通常要做的是在字符串表上建立索引，例如

What I normally do for this is index the table on the string so for example

tbl[mystring1] = 1
tbl[mystring2] = 1

等

添加字符串时，只需使用上面的行，即可处理重复项.然后，您可以使用for ...对do循环读取数据.

When you add a string you simply use the lines above and duplicates will be taken care of. You can then use a for ... pairs do loop to read the data.

如果要计算出现次数

使用类似

if tbl[mystring1] == nil then
  tbl[mystring1] = 1
else
  tbl[mystring1] = tbl[mystring1] + 1
end

在添加周期结束时，如果您需要翻转表，则可以简单地使用

As the end of the addition cycle if you need to turn the table around you can simply use something like

newtbl = {}
for s,c in pairs(tbl) do
  table.insert(newtbl,s)
end

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