はてブのお気に入り情報に基づくRank計算

まだ8317ユーザ分のデータしか無いのですが、とりあえず計算してみた。
べき乗の繰り返し回数が200回、減衰係数が0.85で計算したよ。
この辺を参照:

http://www.kusastro.kyoto-u.ac.jp/~baba/wais/pagerank.html
http://www.sem-r.com/sem/google/20030909005531.html

まず単純にお気に入られ数(データが十分でないので暫定数ですが。)で順位付け

順位	hatenaid	お気に入られ数
1	xxxxx	619
2	xxxxxx	425
3	xxxxxxxxxxx	393
4	xxxxxx	280
5	xxxxxxxxx	235
6	xxxxxxxx	199
7	xxxxx	193
8	xxxxxx	175
9	xxxxxxxxx2	130
10	xxxxxxxx	124
11	xxxxxxxxxxx	120
12	xxxxxxxxx	120
13	xxxxxxx	116
14	xxxxxxx	112
15	xxxx	109
16	xxxxxxxxxx	108
17	xxxxxxx	106
18	xxxxxxxx	103
19	xxxxxxx6	101
20	xxxxxx	99

そしてHatebu Favorite Rankで順位付け

順位	hatenaid	Rank
1	xxxxx	41.7872
2	xxxxxxxxxxx	27.6095
3	xxxxxx	20.6521
4	xxxxxxxx	18.8549
5	xxxxxx	12.2271
6	xxxxxxxxx	11.0448
7	xxxxx	7.37067
8	xxxxxx	7.28443
9	xxxxxxx	6.92857
10	xxxxxx	6.23682
11	xxxxxxxx	6.17176
12	xxxxxxxx	6.12786
13	xxxxxxxx	6.11624
14	xxxxxxxx	5.6269
15	xxxx	5.20906
16	xxxxxxx	5.10285
17	xxxxxxxx	5.05067
18	xxxxxxxxx2	4.76219
19	xxxxxxx	4.70626
20	xxx	4.65832

なにか面白みの無い結果に。
xxxxxxよりxxxxxxxxxxxの方がアクティブな人に気に入られているってことでしょうか。

集計部分のソースコード

超汚いがこんなですよ。

#import <Foundation/Foundation.h>
#import <SimpleDataAccess/SimpleDataAccess.h>
#define CONFIGURATION_FILENAME @"Config"
#define CONFIGURATION_EXT @"plist"


typedef struct _Link {
    int destId;
    int srcId;
    int countOfLinksFromSrc;
} Link;

typedef struct _RankBuffer {
    float rank[2];
} RankBuffer;


#define POWER_COUNT 200
#define DAMPING_FACTOR 0.85
#define LAST(buf, idx) (buf[1-(idx%2)])
#define CURRENT(buf, idx) (buf[(idx%2)])

int main (int argc, const char * argv[]) {
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

    // Configuration
    NSDictionary *configuration = nil;
    NSString *configurationPath = [[NSBundle mainBundle] pathForResource:CONFIGURATION_FILENAME ofType:CONFIGURATION_EXT];
    if (configurationPath) {
        configuration = [NSDictionary dictionaryWithContentsOfFile:configurationPath];
        NSLog(@"configuration = %@", configuration);
    }
    NSDictionary *connectionDictionary = [configuration objectForKey:@"connectionDictionary"];
    if (!connectionDictionary) {
        NSLog(@"connectionDictionary not specified.");
        return -1;
    }
    
    // データベースに簡単アクセスオブジェクトを作成
    SimpleDataAccess *dataAccess = [SimpleDataAccess simpleDataAccessWithConnectionDictionary:connectionDictionary];
    
    NSAutoreleasePool * innerpool = [[NSAutoreleasePool alloc] init];
    
    // ユーザIDの最大値を取得
    NSString *maxSQL = @"select max(record_id) as max_user_id from hatebu_user";
    NSArray *results = [dataAccess executeQueryWithSQL:maxSQL];
    int maxUserId = [[[results lastObject] objectForKey:@"max_user_id"] intValue];
    
    NSLog(@"maxUserId = %d", maxUserId);
    
    if (!maxUserId) {
        NSLog(@"No users found.");
        return -1;
    }
    
    // リンク(お気に入り)情報を取得。ついでにリンク元からのリンク数も取得(後で使う)
    NSString *linksSQL = @"select f.src_id, f.dest_id, s.favoring_count from hatebu_favorite f, hatebu_statistics s ?
                            where f.src_id = s.user_id and s.favoring_count != 0?
                            order by  f.src_id";
    results = [dataAccess executeQueryWithSQL:linksSQL];
    //NSLog(@"results = %@", results);
    
    // リンクリストがオブジェクトだとオーバーヘッドが心配なので配列化
    int countOfLinks = [results count];
    Link *links = (Link *)malloc(countOfLinks * sizeof(Link));
    NSDictionary *aLink = nil;
    int index;
    for (index = 0; index < countOfLinks; index++) {
        aLink = [results objectAtIndex:index];
        links[index].destId = [[aLink objectForKey:@"dest_id"] intValue];
        links[index].srcId = [[aLink objectForKey:@"src_id"] intValue];
        links[index].countOfLinksFromSrc = [[aLink objectForKey:@"favoring_count"] intValue];
    }
    
    // メモリをスリムに
    [innerpool release];
    
    
    // 会員全員分の配列を作成
    int countOfUsers = (maxUserId + 1);
    int sizeofBuffer = countOfUsers * sizeof(RankBuffer);
    RankBuffer *ranks = (RankBuffer *)malloc(sizeofBuffer);
    bzero(ranks,sizeofBuffer);
    
    // べき乗法？でランクを求める
    // PR( A ) = ( 1-d ) +d ( PR ( t1 ) / C ( t1 ) + … + PR ( tn ) / C ( tn ) )
    int counter = 0;
    int indexOfUsers;
    int indexOfLinks;
    for (counter = 0; counter < POWER_COUNT; counter++) {
        // まず、( 1-d )の部分
        for (indexOfUsers = 0; indexOfUsers < countOfUsers; indexOfUsers++) {
            CURRENT(ranks[indexOfUsers].rank, counter) = 1.0 - DAMPING_FACTOR;
        }
        //残りの部分。会員ベースではなくリンクベースでループ
        for (indexOfLinks = 0; indexOfLinks < countOfLinks; indexOfLinks ++) {
            Link link = links[indexOfLinks];
            //#define link links[indexOfLinks]
            CURRENT(ranks[link.destId].rank, counter) += 
                DAMPING_FACTOR * LAST(ranks[link.srcId].rank, counter)/link.countOfLinksFromSrc;
        }
    }
    free(links);

    //DBに投入
    NSString *updateRankSQL = @"update hatebu_statistics set favorite_rank=$1 where user_id=$2";
    //全部を1トランザクションで更新するよ
    [dataAccess beginTransaction];
    for (indexOfUsers = 0; indexOfUsers < countOfUsers; indexOfUsers++) {
        //NSLog(@"%d, %f",indexOfUsers, LAST(ranks[indexOfUsers].rank, counter));
        NSArray *params = [NSArray arrayWithObjects:
            [NSNumber numberWithFloat:LAST(ranks[indexOfUsers].rank, counter)],
            [NSNumber numberWithInt:indexOfUsers],
            nil];
        [dataAccess executeUpdateWithSQL:updateRankSQL parameters:params];
    }
    [dataAccess commitTransaction];
    //更新終わり

    free(ranks);
    [pool release];
    return 0;
}