in reply to Re: Exceptional sorting
in thread Exceptional sorting

It is times. Station a: (sorted)
{Train 0 => 1230, Train 1 => 1244, Train 2 => 1245 , Train 3 => 1247 }
Station b: Train 3 does not stop here, so time is 0000. But I know it is following Train 1.
{Train 1 => 1245, Train 2 => 0000 , Train 3 => 1248 }
I will take the existing order of trains, and calculate the next station.
But trains can be overtaken by other trains in which case I will have a time for the train. So if as station c Train 1 overtakes Train 3 but Train 2 has no time the array would be { Train 0 => 1245, Train 1 => 1255, Train 2 => 0000, Train 3 = 1250 }. In that case my sorting needs to set Train 1at the end, while the other trains need to be kept in order. It is not 5 entries but a couple of 100000s of times that need to be sorted.

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Re: Exceptional sorting
by Abigail-II (Bishop) on May 25, 2004 at 11:51 UTC
    Well, then you basically have two-dimensional data, from which more information can be deduced than the one-dimensional problem you first presented. I'd work with the two-dimensional data, and not flatten out all the times in a big list.

    Abigail

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Re: Re: Re: Exceptional sorting
by Corion (Patriarch) on May 25, 2004 at 11:50 UTC

    I believe that you can't get the topology of the train tracks and stations from the data you supply. You have the presented following table :

    Station aStation bStation c
    Train 01230????1245
    Train 1124412451255
    Train 2124500000000
    Train 3124712481250

    and you want to read from that table the following train track layout:

    Station a       Station b     Station c
 --[]------->-------[]------>------[]---
         \     (Train 0,1,2)    /
          \                    /
           \-------->---------/
                (Train 3)

    [download]

    If that's what you want, it will be impossible, so you have to show much more of the implicit external knowledge about when one train overtakes another train and other rules which you don't mention.

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[d/l]
Re: Re: Re: Exceptional sorting
by Solo (Deacon) on May 25, 2004 at 14:45 UTC
    I will take the existing order of trains, and calculate the next station.
    So, you want to create a function that will predict, based on the times for the N previous stations, what time the trains will arrive at station N+1?

    --Solo
    --
    You said you wanted to be around when I made a mistake; well, this could be it, sweetheart.
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