LCOV - code coverage report
Current view: top level - expand - tradeweight.cc (source / functions) Hit Total Coverage
Test: Test Coverage for xapian-core 4ba52dacf4fb Lines: 6 6 100.0 %
Date: 2019-05-20 14:58:19 Functions: 1 1 100.0 %
Branches: 0 0 -

           Branch data     Line data    Source code
       1                 :            : /** @file tradeweight.cc
       2                 :            :  * @brief Xapian::TradEWeight class - The TradWeight scheme for query expansion.
       3                 :            :  */
       4                 :            : /* Copyright (C) 2013 Aarsh Shah
       5                 :            :  *
       6                 :            :  * This program is free software; you can redistribute it and/or
       7                 :            :  * modify it under the terms of the GNU General Public License as
       8                 :            :  * published by the Free Software Foundation; either version 2 of the
       9                 :            :  * License, or (at your option) any later version.
      10                 :            :  *
      11                 :            :  * This program is distributed in the hope that it will be useful
      12                 :            :  * but WITHOUT ANY WARRANTY; without even the implied warranty of
      13                 :            :  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
      14                 :            :  * GNU General Public License for more details.
      15                 :            :  *
      16                 :            :  * You should have received a copy of the GNU General Public License
      17                 :            :  * along with this program; if not, write to the Free Software
      18                 :            :  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
      19                 :            :  */
      20                 :            : 
      21                 :            : #include <config.h>
      22                 :            : 
      23                 :            : #include "expandweight.h"
      24                 :            : #include <cmath>
      25                 :            : 
      26                 :            : using namespace std;
      27                 :            : 
      28                 :            : namespace Xapian {
      29                 :            : namespace Internal {
      30                 :            : 
      31                 :            : double
      32                 :       8142 : TradEWeight::get_weight() const
      33                 :            : {
      34                 :       8142 :     double reldocs_without_term = get_rsize() - stats.rtermfreq;
      35                 :            :     double num, denom;
      36                 :       8142 :     num = (stats.rtermfreq + 0.5) * (get_dbsize() - stats.termfreq - reldocs_without_term + 0.5);
      37                 :            : 
      38                 :       8142 :     denom = (stats.termfreq - stats.rtermfreq + 0.5) * (reldocs_without_term + 0.5);
      39                 :            : 
      40                 :       8142 :     double tw = log(num / denom);
      41                 :       8142 :     return stats.multiplier * tw;
      42                 :            : }
      43                 :            : 
      44                 :            : }
      45                 :            : }

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