BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  How to sort Lines in a StringList depending on their length          BorlandTalk.com Forum Index -> C++ Builder (VCL Components Usage) View previous topic :: View next topic   Author Message Oren (Halvani.de) Guest Posted: Thu Jul 24, 2003 7:51 pm    Post subject: How to sort Lines in a StringList depending on their length hi dear builders, I got a question - is it possible to sort Lines in a StringList depandent on their length ?? for example: "Here is test.." "Here is more text.." "Here is even more text.." Is this possible ?? Oren Back to top Hans Galema Guest Posted: Thu Jul 24, 2003 8:12 pm    Post subject: Re: How to sort Lines in a StringList depending on their len Oren (Halvani.de) wrote: Quote: I got a question - is it possible to sort Lines in a StringList depandent on their length ?? "Here is test.." "Here is more text.." "Here is even more text.." Traverse the StringList twice. Start with Sorted = false; In the first pass add the length in front of the line. It will then look like: "0014 Here is test.." "0019 Here is more text.." "0024 Here is even more text.." Now set Sorted to true. In the second pass remove the numbers. Hans. Back to top Oren (Halvani.de) Guest Posted: Thu Jul 24, 2003 8:14 pm    Post subject: Re: How to sort Lines in a StringList depending on their len Thanks Hans, good idea :-) I'll try your suggestion.. Oren Back to top Rhys Sage Guest Posted: Thu Jul 24, 2003 8:15 pm    Post subject: Re: How to sort Lines in a StringList depending on their len Easy as pie. Create 3 TStringLists. The first contains your original data. The second contains nothing. The third is a temprorary list. (for speed) run through List1 (your data) put the index of the longest item into your temprorary list. if it's longer, clear the list and put it into the list At the end of the run, put the items listed from List one into List two and clear the temprorary list. Also delete the items from List1 keep repeating the process until you have no data in List1 or the Temprorary list Easy peasy. -- Yours, Rhys Sage. www.sageworld.freeserve.co.uk for code snippets and software downloads. -- Vini vidi vici -- (Team Zip) "Oren (Halvani.de)" <neroniker (AT) gmx (DOT) de> wrote Quote: hi dear builders, I got a question - is it possible to sort Lines in a StringList depandent on their length ?? for example: "Here is test.." "Here is more text.." "Here is even more text.." Is this possible ?? Oren Back to top Hans Galema Guest Posted: Thu Jul 24, 2003 8:33 pm    Post subject: Re: How to sort Lines in a StringList depending on their len Rhys Sage wrote: Quote: run through List1 (your data) put the index of the longest item into your temprorary list. if it's longer, clear the list and put it into the list Dont understand that. A longer index ? Or do you mean a higher index ? In the last sentence yoou use twice the word list. Which list's ? Quote: At the end of the run, put the items listed from List one into List two and clear the temprorary list. Also delete the items from List1 keep repeating the process until you have no data in List1 or the Temprorary Still don't understand the algorithm. How many passes would this RhysBubbleSort take for 1000 lines ? Hans. Back to top Rhys Sage Guest Posted: Thu Jul 24, 2003 9:51 pm    Post subject: Re: How to sort Lines in a StringList depending on their len It's not a bubble-sort. It's much faster than a bubble sort. Example List A starts with 1 2 3 4 3 2 23 23 12 23 23 The temprory list at the end of the first pass would have the indexes of all the 23s as they're the highest values: thus 7,8,11,12 List B then has 23,23,23,23 added List A has values 7,8,11,12 deleted. Now ListA contains 1, 2, 3, 4,3,2,12 The process repeats with an ever-decreasing List length. I did it with a TStringGrid and sorted 1500 items in less than a second (on a 166Mhz CPU). I compared that with a true bubble-sort which took a minute or two. I'd say my method works just fine. -- Yours, Rhys Sage. www.sageworld.freeserve.co.uk for code snippets and software downloads. -- Vini vidi vici -- (Team Zip) "Hans Galema" <j.m.galema.dontusethis (AT) maartens (DOT) nl> wrote Quote: Rhys Sage wrote: run through List1 (your data) put the index of the longest item into your temprorary list. if it's longer, clear the list and put it into the list Dont understand that. A longer index ? Or do you mean a higher index ? In the last sentence yoou use twice the word list. Which list's ? At the end of the run, put the items listed from List one into List two and clear the temprorary list. Also delete the items from List1 keep repeating the process until you have no data in List1 or the Temprorary Still don't understand the algorithm. How many passes would this RhysBubbleSort take for 1000 lines ? Hans. Back to top JD Guest Posted: Thu Jul 24, 2003 11:37 pm    Post subject: Re: How to sort Lines in a StringList depending on their len Now now boys. Play nice. Both methods require accessing the actual strings more than once. I'll bet ... if you create an array that holds the length and the index of that length, sort it and then use Move(), that even a bubble-sort on the array will out perform both suggested methods. However, I doubt if one could devise a method more simple than adding the length to the string and letting the list sort it's self. Just a note on that method though: the length should have more leading zeros. ~ JD Back to top Rhys Sage Guest Posted: Fri Jul 25, 2003 12:56 am    Post subject: Re: How to sort Lines in a StringList depending on their len An interesting alternative would be a tree sort. -- Yours, Rhys Sage. www.sageworld.freeserve.co.uk for code snippets and software downloads. -- Vini vidi vici -- (Team Zip) Back to top JD Guest Posted: Fri Jul 25, 2003 3:31 am    Post subject: Re: How to sort Lines in a StringList depending on their len "Rodolfo Frino" <rodolfofrino (AT) yahoo (DOT) com> wrote: Quote: or a sort of tree sort LOL!! Cute - real cute. ~ JD Back to top Hans Galema Guest Posted: Fri Jul 25, 2003 8:30 am    Post subject: Re: How to sort Lines in a StringList depending on their len JD wrote: Quote: Now now boys. Play nice. Don't we ? Quote: Both methods require accessing the actual strings more than once. I'll bet ... if you create an array that holds the length and the index of that length, sort it and then use Move(), that even a bubble-sort on the array will out perform both suggested methods. Using an array, quicksort and Move(), yes. Using an array, bubblesort and Move(), I think yes to. But that depends on the speed of Move(). But now that I think of it: every Move() would alter the sequence of strings so after one Move() you could not find the other strings on their index. Unless you adjusted their index for that. Maybe not using Move() and just ading to a second StringList ? But please show the code. Quote: However, I doubt if one could devise a method more simple than adding the length to the string and letting the list sort it's self. Just a note on that method though: the length should have more leading zeros. With only three lines there were to much ;-) Here are the results of ading the size, sorting and removing on a 500Mz: Size: 305658 Lines: 1973 Ading size: 46 ms. Sorting: 74 ms. Removing size: 11 ms. Usedtime: 131 ms. And here is the used code: TStringList *StringList = new TStringList; StringList->Sorted = false; StringList->Text = RichEdit1->Text; int starttickcount = GetTickCount(); int nlines = StringList->Count; int linenr = -1; while (++linenr < nlines ) { AnsiString Line = StringList->Strings [linenr]; char linebuf [5000+2]; sprintf ( linebuf, "%06d %s", Line.Length(), Line.c_str() ); StringList->Strings [linenr] = linebuf; } StringList->Sorted = true; // This does the actual sorting StringList->Sorted = false; linenr = -1; while (++linenr < nlines ) { AnsiString Line = StringList->Strings [linenr]; StringList->Strings [linenr] = Line.SubString ( 8, 5000 ); } int elapsedtime = GetTickCount() - starttickcount; Memo1->Lines->Add ( "Elapsed time: " + IntToStr ( elapsedtime ) + " ms."); RichEdit4->Clear(); RichEdit4->Text = StringList->Text; delete StringList; The credits for this speed go to the sorting algorithm of the TStringList. Which will be a quick sort I think. <Rys> Quote: The process repeats with an ever-decreasing List length. I did it with a TStringGrid and sorted 1500 items in less than a second (on a 166Mhz CPU). /Rys With a StringGrid ? A GRID ? You said to use three StringLists. With a cpu speed nearly four times slower and not using quicksort, that's quite good I think. Hans. Back to top Hans Galema Guest Posted: Fri Jul 25, 2003 8:34 am    Post subject: Re: How to sort Lines in a StringList depending on their len Hans Galema wrote: Quote: Rys Sorry, <Rhys> ! Hans. Back to top Todd Brylski Guest Posted: Fri Jul 25, 2003 10:33 am    Post subject: Re: How to sort Lines in a StringList depending on their len "Oren (Halvani.de)" <neroniker (AT) gmx (DOT) de> wrote Quote: hi dear builders, I got a question - is it possible to sort Lines in a StringList depandent on their length ?? TStringList has a CustomSort method. You can use it like this: // define a custom sort function int __fastcall SortByLength( TStringList* List, int Index1, int Index2 ) { return List->Strings[Index1].Length() - List->Strings[Index2].Length(); } void __fastcall TForm2::Sort1Click(TObject *Sender) { AStringList->CustomSort( SortByLength ); } Todd Back to top Hans Galema Guest Posted: Fri Jul 25, 2003 1:42 pm    Post subject: Re: How to sort Lines in a StringList depending on their len Todd Brylski wrote: Quote: TStringList has a CustomSort method. You can use it like this: BCB3 does not implement that. BCB5 does. It took 27 ms instead of the 130 ms for the linesize ading as mentioned in this thread already. Thanks for the info and code. Hans. Back to top Oren (Halvani.de) Guest Posted: Fri Jul 25, 2003 11:58 pm    Post subject: Re: How to sort Lines in a StringList depending on their len Thanks for all the postings... 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