Re: Table generation issue

[askok@...]

Just remember that each string created is immutable in 
Lua; meaning if you anyways end up slicing the long string 
to the smaller ones in Lua, you're not essentially 
changing anything.


On Tue, 21 Nov 2006 13:40:54 -0800 (PST)
 Steve Heller <steveheller@sbcglobal.net> wrote:
> Actually, at this point it appears that the main time
> was in the table "embedding", so I changed it to
> return a table of tables, one subtable for each
> dataGenerator object. That about doubled the overall
> throughput.
>
> But now I have a different problem, which is that
> actually retrieving the data inside my C++ program is
> taking a long time, mostly due to "luatolstring". At
> this point, I'm thinking maybe I have to return the
> data as one long string rather than a lot of small
> ones. That might actually be better for my application
> because that is the form that the data is eventually
> needed in.
>
> By the way, I really appreciate the help from
> everyone. Thanks!
>
> --- Asko Kauppi <askok@dnainternet.net> wrote:
>
> > My suggestions, since it's easy for you to measure
> > if there's any  
> > effect:
> >
> > - local data_i= data[i]
> > to cache the value, and avoid a number of table
> > accesses (locals are  
> > fast)
> > - local data_i1= data[i][1]
> > same thing
> > - is 'data[i]' a table of two values that do not
> > change?  If so, just  
> > use it, not making a copy?
> >
> >
> > >     local data = dataGenerator()
> > >
> > > 	local subTable = {}
> > > 	local subTableBlock = {}
> > > 	local subTableType
> > > 	
> > >     for i, element in ipairs(data) do
> > local data_i= data[i]
> > local data_i1= data_i[1]
> > >         if data_i1 == "<type>" then
> > > 			subTableType = data_i[2]
> > >         elseif data_i1 == "</type>" then
> > >         elseif data_i1 == "<block>" then
> > >             subTableBlock =
> > > {Number=data_i[2],Dup=data_i[3]}
> > >         elseif data_i1 == "</block>" then
> > > 			subTable[#subTable+1] = subTableBlock
> > >         else
> > >             if trim(data_i[2]) ~= "" then
> > >                 subTableBlock[#subTableBlock+1] =
> > data_i	-- in case it only has [1] and [2]
> > >             end
> > >         end
> > >     end
> > >
> > >     return subTable, subTableType
> > >
> > > end
> > >
> >
> >
> >
> > On 21.11.2006, at 17.40, Steve Heller wrote:
> >
> > > Unfortunately, my timing runs show that your
> > > suggestion makes no measurable difference. Any
> > other
> > > suggestions would be welcomed.
> > >
> > > --- Romulo Bahiense <romulo@icontroller.com.br>
> > wrote:
> > >
> > >> I believe the problem is not table allocation,
> > but
> > >> index access and
> > >> length calculation ('#' operator).
> > >>
> > >> Try this one:
> > >>
> > >> function
> > createFieldDataEntriesForOneDataGenerator(
> > >> dataGenerator )
> > >>
> > >>      local data = dataGenerator()
> > >>
> > >>      local iSubTable      = 0
> > >>      local iSubTableBlock = 0
> > >>
> > >>      local subTable      = {}
> > >>      local subTableBlock = {}
> > >>
> > >>      local subTableType
> > >>
> > >>      for i, element in ipairs(data) do
> > >>          local a, b, c = element[ 1 ], element[ 2
> > ],
> > >> element[ 3 ]
> > >>          if a == "<type>" then
> > >>              subTableType = b
> > >>          elseif a == "</type>" then
> > >>              -- do nothing
> > >>          elseif a == "<block>" then
> > >>              subTableBlock = {Number=b,Dup=c}
> > >>          elseif a == "</block>" then
> > >>              iSubTable = iSubTable + 1
> > >>              subTable[iSubTable] = subTableBlock
> > >>          else
> > >>              if trim(b) ~= "" then
> > >>                  iSubTableBlock = iSubTableBlock
> > + 1
> > >>                  subTableBlock[ iSubTableBlock ]
> > =
> > >> {a,b}
> > >>              end
> > >>          end
> > >>      end
> > >>
> > >>      return subTable, subTableType
> > >> end
> > >>
> > >> Note that, in this code, 'data[i]' is the same as
> > >> 'element', because
> > >> ipairs return key and value.
> > >>
> > >> --rb
> > >>
> > >