API sort

From WoWWiki

From TableLibraryTutorial of lua-users.org.

table.sort(table [, comp])

Sort the elements of a table in-place (i.e. alter the table).

> t = { 3,2,5,1,4 }
> table.sort(t)
> = table.concat(t, ", ")  -- display sorted values
1, 2, 3, 4, 5

If the table has a specified size only the range specified is sorted, e.g.,

> t = { 3,2,5,1,4; n=3 }   -- construct a table with user size of 3
> table.sort(t)            -- sort will be limited by user size
> = table.concat(t, ", ")  -- only specified size is concatenated as well
2, 3, 5

Warning: Setting the range of the sort is no longer possible since table.setn is no longer supported (setting n=3 will not set the size of the table to 3) Yssaril 05

31, 23 March 2008 (UTC)

A comparison function can be provided to customise the element sorting. The comparison function must return a boolean value specifying whether the first argument should be before the second argument in the sequence. The default behaviour is for the < comparison to be made. For example, the following behaves the same as no function being supplied:

> t = { 3,2,5,1,4 }
> table.sort(t, function(a,b) return a<b end)
> = table.concat(t, ", ")
1, 2, 3, 4, 5        

We can see if we reverse the comparison the sequence order is reversed.

> table.sort(t, function(a,b) return a>b end)
> = table.concat(t, ", ")
5, 4, 3, 2, 1

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Notes:

Sorting tables containing non-numeric keys using a custom comparison function does not work. The function will not get called, and the table will be sorted according to some kind of internal function.

Sorting by Name

There is a user-function you can write that will sort a table by name during a for function.

function pairsByKeys (t, f)
	local a = {}
		for n in pairs(t) do table.insert(a, n) end
		table.sort(a, f)
		local i = 0      -- iterator variable
		local iter = function ()   -- iterator function
			i = i + 1
			if a[i] == nil then return nil
			else return a[i], t[a[i]]
			end
		end
	return iter
end

This function will replace the pairs function in a for statement. Example:

for title,value in pairsByKeys(randomtable) do
	DEFAULT_CHAT_FRAME:AddMessage(title..", "..value);
end

This will print all the variables in randomtable alphabetically!

 

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This is a Lua function and documented as part of the World of Warcraft API