How to sort an array alphabetically based on its values' property

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#1

I want to be able to take an array and sort it alphabetically based on the Name property of the objects inside.
For example, if we have an input of:

{dog, cat, hamster, turtle, cat}

then output should be:

{cat, cat, dog, hamster, turtle}

(every variable contains a Name (i.e dog.Name = “Dog”, cat.Name = “cat”, etc), and it sorts alphabetically based on that)

Note that the same value can appear more than once, like in the example above where "cat" appears twice.
I’ve actually already found a “solution” but… it is incredibly hacky.

Current Solution: 
    local items = localItemInventory:GetChildren()
	local alphabeticallySortedItems = {}
	local alphabeticallySortedKeys = {}
	
	for i, item in ipairs(items) do
		local updatedItemName = item.Name
		local loopCount = 0
		while table.find(alphabeticallySortedKeys, updatedItemName) do
			loopCount += 1
			updatedItemName = item.Name .. tostring(loopCount)
		end
		table.insert(alphabeticallySortedKeys, updatedItemName)
	end
	table.sort(alphabeticallySortedKeys)
	for i, item in ipairs(items) do
		for i, v in ipairs(alphabeticallySortedKeys) do 
			if item.Name == string.sub(v, 1, string.len(item.Name)) then
				alphabeticallySortedItems[i] = item
				alphabeticallySortedKeys[i] = "ABCDEFGHJILKMNAOP"
				break
			end
		end
	end

Any better solutions or methods would be appreciate :slight_smile:

#2

This should do it!

local t = {'b', 'a', 'c'};

table.sort(t, function(a,b)
return a:lower() < b:lower();
end);

print(t[1], t[2], t[3]);
1 Like
#3

This is correct, but I’d like to point out that semicolons aren’t required in Lua.

#4

If they don’t effect the quality or functionality of the code, is there really an issue?
also I guess, you could say force of habit lol.

(also I don’t want to get off topic, so I’ll just leave it at that.)

#5

If it’s a force of habit, it’s fine. I just wanted to point it out.

#6 
local function SortTable(array)
      table.sort(array)
      return array
end

just do sort

#7

@koyugaki is mostly correct but I think they may have misunderstood your question. You do need to use table.sort with a custom comparator:

table.sort(t, function(a, b) return a.Name < b.Name end)

You can add :lower() if you need.

1 Like
#8

I really thought that wouldn’t work but I tried it and… it works… so well… thank you very much.

Unfortunately, I have no idea how that works at all… Could anyone explain what the second argument does?

#9

its like looping trough the table and compare the values

for _,a in pairs(table) do
      for _,b in pairs(table) do
           if a:lower() < b:lower() then
                  --does the sorting
           end
     end
end

also you can just do table.sort(array)

1 Like
#10

I managed to figure out how to make their solution work with specific properties, but thank you for that information nonetheless :slight_smile:

#11

I think I kind of understand it now. Thank you, that information about it looping through the tables helped a lot