[MudWalker] Help With Tables

[Kevin Reid]

Blastron <blastron at mac.com> wrote:

> Is it possible to sort one table, say table blah, by another table, 
> table foo, so that items in table blah would appear in the order that
> they appear in table foo?  For instance, if table blah contained A, B,
> D, and F, and table foo contained F, A, E, B, D, and C (in that order),
> whatever function would do that would sort table blah as F, A, B, D.

You would likely get better help with this problem by asking in a Lua
mailing list or other such forum. I'm not particularly familiar with the
language.

  <http://www.lua.org/>
  <http://www.lua.org/manual/5.0/>
  <http://www.lua.org/community.html>

Here's what I came up with after a glance through the manual (you'll
have to add @@ to use this within MudWalker, of course):


local values = {"gamma", "alpha", "epsilon", "delta", "beta"}

local order = {"alpha", "beta", "gamma", "delta", "epsilon"}

function byorder(a, b)
  local aIndex, bIndex
  for orderIndex, orderValue in ipairs(order) do
    if orderValue == a then
      aIndex = orderIndex
    end
    if orderValue == b then
      bIndex = orderIndex
    end
    if ai ~= nil and bi ~= nil then
      return aIndex < bIndex
    end
  end
  return a < b
end

table.sort(values, byorder)

for k, v in pairs(values) do
  print(k, v)
end



> Also, is there a function to see if a particular value exists within a
> table that would return true or false, or, better yet, the location of
> the value within the table or false?

If you find one, let me know. The loop in the byorder() function above
exists only to do that search.



-- 
Kevin Reid