[Qt-interest] Is it a stupid way for sorting?

[Malyushytsky, Alex]

There is no point in sorting any data using widget.
I think you should review help on
void qSort ( RandomAccessIterator begin, RandomAccessIterator end, LessThan lessThan )
in Qt documentation again.
I think it contains pretty good explanation.

The code below should do the job,  but it is not very efficient

bool myCompareFunction(const QString &s1, const QString &s2)
{
     return s1.count("?") < s2.count("?");
}

QStringList sortPatterns(QStringList patterns)
{
     qSort(patterns.begin(), patterns.end(), myCompareFunction);

     return patterns;
}

It is not very efficient cause every time qSort need to compare 2 values it will recount "?".
Better approach might be to compute it only once.

You might use QMap or build another container like QList<int, QStringList::iterator > and sort it
with above mentioned technique,  ( int value will be a count and iterator will give you access to the string . You can use index instead of iterator )

Example of using map for sorting in your case:

QStringList sortPatterns2(QStringList patterns)
{
     QMultiMap < int, QString> map;

     for(int i=0; i<patterns.count(); i++)
     {
          int count = patterns[i].count("?");
          map.insert( count, patterns[i] );
     }


     return map->values ();
}

Regards,
        Alex


-----Original Message-----
From: qt-interest-bounces at trolltech.com [mailto:qt-interest-bounces at trolltech.com] On Behalf Of M. Bashir Al-Noimi
Sent: Wednesday, April 21, 2010 7:12 PM
To: qt-interest at trolltech.com
Subject: Re: [Qt-interest] Is it a stupid way for sorting?

Thanks William,

Actually I took this way because I don't know how I can make sort
process by qSort (I found in Qt documentation something about QMap and
qSort), so could you give me an example explains how to do that?

On 21/04/2010 07:58 م, william.crocker at analog.com wrote:
> See:
>
>       qSort ( RandomAccessIterator begin, RandomAccessIterator end, LessThan lessThan )
>       et. al.
>
> M. Bashir Al-Noimi wrote:
>
>> Hi All,
>>
>> I want to sort QStringList by specific item count so I tried to use QMap
>> for it but I failed but I used QTableWidget instead but without viewing
>> it in the GUI, *is it correct way for sorting? it's slow (and stupid :-[ )?*
>>
>> QStringList sortPatterns(QStringList patterns)
>> {
>>      QStringList result;
>>      QTableWidget *table = new QTableWidget(patterns.count(), 2);
>>      for(int x=0; x<patterns.count(); x++)
>>      {
>>          int count = patterns[x].count("?");
>>          table->setItem(x, 0, new QTableWidgetItem(QString("%1").arg(count, 2, '0')));
>>          table->setItem(x, 1, new QTableWidgetItem(patterns[x]));
>>      }
>>      table->sortItems(0);
>>      for(int x=0; x<patterns.count(); x++)
>>          result<<table->item(x, 1)->text();
>>      return result;
>> }
>>
>>
>>
>> --
>> Best Regards
>> Muhammad Bashir Al-Noimi
>> My Blog: http://mbnoimi.net
>>
>>
>> ------------------------------------------------------------------------
>>
>> _______________________________________________
>> Qt-interest mailing list
>> Qt-interest at trolltech.com
>> http://lists.trolltech.com/mailman/listinfo/qt-interest
>>
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>

--
Best Regards
Muhammad Bashir Al-Noimi
My Blog: http://mbnoimi.net

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