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Add a penalty score to tracks with low playcount in the last weeks.

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This commit is contained in:
Uwe L. Korn 2013-07-11 19:06:20 +02:00
parent ef9472d1e8
commit 5b164639ac
2 changed files with 44 additions and 13 deletions
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47
src/libtomahawk/database/DatabaseCommand_TrendingTracks.cpp
View File

@ -22,6 +22,8 @@
#include "database/TomahawkSqlQuery.h"
#include "Track.h"
#include <algorithm>
namespace Tomahawk {
DatabaseCommand_TrendingTracks::DatabaseCommand_TrendingTracks( QObject* parent )
@ -39,7 +41,6 @@ void
DatabaseCommand_TrendingTracks::exec( DatabaseImpl* dbi )
{
Q_D( DatabaseCommand_TrendingTracks );
TomahawkSqlQuery query = dbi->newquery();
QString limit;
if ( d->amount > 0 )
@ -50,10 +51,28 @@ DatabaseCommand_TrendingTracks::exec( DatabaseImpl* dbi )
QDateTime now = QDateTime::currentDateTime();
QDateTime _1WeekAgo = now.addDays( -7 );
QDateTime _2WeeksAgo = now.addDays( -14 );
QDateTime _3WeeksAgo = now.addDays( -21 );
// TODO:
// -> Look at absolute playcount, an increase from 1 to 4 plays per week is currently considered very high
uint peersLastWeek = 1; // Use a default of 1 to be able to do certain mathematical computations without Div-by-0 Errors.
{
// Get the number of active peers in the last week.
// We could just use the number of peers instead but that would include old peers that may have been inactive for a long while.
QString peersLastWeekSql = QString(
" SELECT COUNT(DISTINCT source ) "
" FROM playback_log "
" WHERE playback_log.source IS NOT NULL " // exclude self
" AND playback_log.playtime >= %1 "
).arg( _1WeekAgo.toTime_t() );
TomahawkSqlQuery query = dbi->newquery();
query.prepare( peersLastWeekSql );
query.exec();
while ( query.next() )
{
peersLastWeek = std::max( 1u, query.value( 0 ).toUInt() );
}
}
QString timespanSql = QString(
" SELECT COUNT(*) as counter, track "
" FROM playback_log "
@ -63,16 +82,20 @@ DatabaseCommand_TrendingTracks::exec( DatabaseImpl* dbi )
);
QString lastWeekSql = timespanSql.arg( _1WeekAgo.toTime_t() ).arg( now.toTime_t() );
QString _1BeforeLastWeekSql = timespanSql.arg( _2WeeksAgo.toTime_t() ).arg( _1WeekAgo.toTime_t() );
QString _2BeforeLastWeekSql = timespanSql.arg( _3WeeksAgo.toTime_t() ).arg( _2WeeksAgo.toTime_t() );
QString formula = QString(
" ( lastweek.counter / weekbefore.counter ) "
" * "
" max(0, 1 - (%1 / (4*min(lastweek.counter, weekbefore.counter )) ) )"
).arg( peersLastWeek );
QString sql = QString(
" SELECT track.name, artist.name, ( lastweek.counter - weekbefore.counter ) as slope1, max( weekbefore.counter - week2before.counter, 1 ) as slope2, ( ( lastweek.counter - weekbefore.counter ) / max( weekbefore.counter - week2before.counter, 1 ) ) as trending "
" FROM ( %1 ) lastweek, ( %2 ) weekbefore, ( %3 ) week2before, track, artist "
" WHERE lastweek.track = weekbefore.track AND weekbefore.track = week2before.track "
" SELECT track.name, artist.name, ( %4 ) as trending "
" FROM ( %1 ) lastweek, ( %2 ) weekbefore, track, artist "
" WHERE lastweek.track = weekbefore.track "
" AND track.id = lastweek.track AND artist.id = track.artist "
" AND ( lastweek.counter - weekbefore.counter ) > 0"
" ORDER BY slope1 DESC %4 "
).arg( lastWeekSql ).arg( _1BeforeLastWeekSql ).arg( _2BeforeLastWeekSql ).arg( limit );
" ORDER BY trending DESC %3 "
).arg( lastWeekSql ).arg( _1BeforeLastWeekSql ).arg( limit ).arg( formula );
TomahawkSqlQuery query = dbi->newquery();
query.prepare( sql );
query.exec();
@ -85,7 +108,7 @@ DatabaseCommand_TrendingTracks::exec( DatabaseImpl* dbi )
if ( !track )
continue;
tracks << QPair< double, track_ptr >( query.value( 4 ).toDouble(), track );
tracks << QPair< double, track_ptr >( query.value( 2 ).toDouble(), track );
}
emit done( tracks );

10
src/libtomahawk/database/DatabaseCommand_TrendingTracks.h
View File

@ -29,7 +29,15 @@ class DatabaseCommand_TrendingTracksPrivate;
* Find tracks that trend among your friends.
*
* At the moment the most trending tracks are those with the highest quotient of
* plays in the last week and the week before.
* plays in the last week and the week before with a penalty applied to those with
* a low playcount.
*
* The exact calculation is done as follows:
*
* w_1(t) := playcount this week of track t
* w_2(t) := playcount one week before of track t
* p := active peers (with at least one play) in the last week
* trending(track) = (w_1(t) / w_2(t)) * (1 - p / (4 * min(w_1(t), w_2(t))))
*/
class DLLEXPORT DatabaseCommand_TrendingTracks : public Tomahawk::DatabaseCommand
{