Sorting lua tables by arbitrary values

Question

I have a table with the following structure:

table = {
    [1] = {"something", "high"}
    [2] = {"something else", "low"}
    [3] = {"something further", "medium"},
    [4] = {"yet more something", "medium"},
}

What I want to do, is to use a delegate function to sort that table with table.sort() so that the priority variable (high, low, medium, etc) orders the list with high being followed in the list, followed by medium and then low. How would I go about doing this?

Martin Ender · Accepted Answer · 2013-03-16 16:56:30Z

4

You seem to know how table.sort works, so where are you stuck? Simply create a lookup table that translates priority names into integers and compare those:

priorities = {high = 2, medium = 1, low = 0}
table.sort(t, function(e1, e2)
    return priorities[e1[2]] > priorities[e2[2]]
end)

answered Mar 16, 2013 at 16:56

Martin Ender

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Egor Skriptunoff · Accepted Answer · 2013-03-16 18:21:49Z

0

table.sort(t, 
  function(e1, e2)
    return e1[2]:sub(-1) < e2[2]:sub(-1)
  end
)

answered Mar 16, 2013 at 18:21

Egor Skriptunoff

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3 Comments

Martin Ender Over a year ago

Funny idea, but quite obscure and inflexible, don't you think?

Martin Ender Over a year ago

I just wanted to add a note of caution, as this is a very compact solution but one that I don't think should go into production code ;)

Egor Skriptunoff Over a year ago

@Ephemeralis - Please don't embed my solution into production code :-)

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