[fpc-pascal] TSortedCollection dupes ordering

[waldo kitty]

On 2/6/2014 4:23 AM, Frederic Da Vitoria wrote:
> Then my trick does not work for you because it hides the fact that the records
> are identical.

actually, the problem comes when referencing the IndexOf() the record... 
IndexOf(Item) is passed (unmodified) thru a couple of routines to finally end up 
here as 'idx'... IndexOf() being the TSortedCollection IndexOf() routine...

Procedure LogTLEPerApo(tleRecord: PTLERec; idx: sw_integer; var oFile: text);

begin
   WriteLogLine(AppLogFile,0,
              PadLeft(IntToStr(idx),5)
     + '  ' + PadRight(tleRecord^.catnbr^,5)
     + '  ' + PadRight(tleRecord^.cospar^,8)
     + '  ' + PadRight(tleRecord^.satname^,27)
     + '  ' + 
PadRight(AddChar('0',FloatToStrF(tleRecord^.epoch,ffFixed,15,8),14),15)
            + PadRight(displayEpochString(tleRecord^.epoch),19)
     + '  ' + PadLeft(FloatToStrF(tleRecord^.Perigee,ffFixed,15,8),16)
     + ' x ' + PadLeft(FloatToStrF(tleRecord^.Apogee,ffFixed,15,8),16)
     + ' x ' + PadLeft(FloatToStrF(tleRecord^.Inclination,ffFixed,15,8),16)
     + '  ' + PadLeft(FloatToStrF(tleRecord^.SMajAxisKM,ffFixed,15,8),16)
     + '  ' + PadLeft(FloatToStrF(tleRecord^.MMPeriod,ffFixed,15,8),16)
     + '  ' + PadLeft(FloatToStrF(tleRecord^.SMAPeriodC,ffFixed,15,8),16)
     + '  ' + PadLeft(FloatToStrF(tleRecord^.SMAPeriodP,ffFixed,15,8),16)
   );
   WriteOUTFile(tleRecord,oFile);
   inc(tot_TLEs_written);
end;


> You need to give to someone the responsibility of giving the secondary key.

that's not going to happen... anyone can generate these records and make them 
available to others for use... i'm aware of at least 5 different groups and 
several owners of the objects who are generating these...

> If I understand what you wrote correctly, there is already
> something which could be used as a tertiary key, but it doesn't really work
> because the way it is filled is not consistent across the different sources.

right... for the same reason as above...

> If I were you, I'd keep this tertiary key data (I guess it is meaningful, so
> you can't remove it),

right... it is part of the format... some records don't even have this tertiary 
key filled in...

> and I'd create my own secondary key inside the TSortedCollection descendant.

hummm... one group does something similar but i currently don't have any method 
of doing this... in all actuality i should probably be doing this in a sql 
database but the overhead of processing speed and storage space is more than i 
want to deal with... especially since a full processing run using all options 
takes less than a minute for ~40000 records and a previous tool (limited to 64k) 
takes almost 30 minutes...

> I'd use 2 compare functions,
>   - one which works as your current one but wouldn't be declared as a compare
> function (you could call it CheckPrimaryExists) and which would return 0 if the
> primary key already exists
>   - and one which uses both the primary and the secondary key as Jim suggested.
>
> The algo (when duplicates are allowed) would be something like:
> if primary key exists
>      then set secondary key to a number
> insert the data

definitely something for me to contemplate on...

> Note that depending on the total number of rows, you could use a general counter
> for the secondary key, no need to fetch the value of the last secondary key for
> the same primary key.
>
> You'd get something like (primary key / secondary key)
> A / 0
> B / 0
> B / 1 (duplicate detected, first secondary key generated)
> C / 0
> C / 2 (duplicate detected, second secondary key generated, note that there is no C1)
> ...
>
> ... and now that I think of it, you don't need 2 compare functions, the second
> one should work for both usages.

this is one of the things i like about talking about problems... while others 
may not be fully aware of the data, they can still come up with ideas on how to 
handle situations... one of the things i used to do was to talk to a mechanic 
friend... i'd convert my tasks and problems to something vehicle related so that 
he could see it from his mechanic's point of view and then he'd ask about doing 
it like "this" in vehical mechanic terms which i'd convert back to programming 
and suddenly have a workable solution... he helped me solve more problems in 
this way than i can count and he barely knew where the "big red switch" was on 
the computers ;) ;) ;)


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