Lua, Tables: merge values of duplicate keys and remove duplicates

Question

I've started fiddling a lot with lua recently, but I can't for my life figure this out.

Let's say I have a string that looks like this:

s = "a=x a=y b=z a=x"

I want to remove all duplicates and merge the values of duplicate keys into a table, so that I get:

t = {
a = {x,y},
b = {z},
}

I've been pondering about this for way too long. Any help is appreciated!

lhf · Accepted Answer · 2013-04-29 12:54:44Z

2

Try this:

s="a=x a=y b=z a=x"

s=s.." "
t={}
for k,v in s:gmatch("(.-)=(.-)%s+") do
        if t[k]==nil then t[k]={} end
        t[k][v]=true
end

for k,v in pairs(t) do
        for z in pairs(v) do print(k,z) end
end

edited Apr 29, 2013 at 12:54

answered Apr 29, 2013 at 12:40

lhf

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3 Comments

Easypeasy Over a year ago

You make it seem so ridiculously easy. It seems to do what I want it to do - now i'll try to break it down to get a better understanding. Many thanks!

Easypeasy Over a year ago

Quick question: (I have searched) How would I go about to print a nested value from this table. For example, print(t.a[1]) doesn't work.

lhf Over a year ago

@Easypeasy, that's exactly what for z in pairs(v) do print(k,z) end does.

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