將日期按小時，天，周，月，年進行聚類數據目標c

Question

我有一個具有屬性時間和數量的Stat對象。我有一個（按時間排序）每小時進入的這些對象的列表。我想要集羣顯示。 有沒有一種很好的方式來在目標c中按時間聚類數據？或比以下天真的算法更好的算法？

這是每週做一個例子。其他類似，但您更改日期組件。

-(void) makeWeeklyData{ 

    Stat *prev = self.hourlyData[0]; 
    NSInteger sum = 0; 
    NSMutableArray *weeklyData = [NSMutableArray array]; 
    for (CSInstallStat *data in self.hourlyData) { 
     NSDateComponents *itemComps = [[NSCalendar currentCalendar] components:kCFCalendarUnitWeekOfYear | NSCalendarUnitMonth | NSCalendarUnitYear fromDate:data.time]; 
     [itemComps setCalendar:[NSCalendar currentCalendar]]; 

     NSDateComponents *currComps = [[NSCalendar currentCalendar] components:kCFCalendarUnitWeekOfYear | NSCalendarUnitMonth | NSCalendarUnitYear fromDate:prev.time]; 
     [currComps setCalendar:[NSCalendar currentCalendar]]; 

     if ([itemComps weekOfYear] == [currComps weekOfYear] && [itemComps month] == [currComps month] && [itemComps year] == [currComps year]) {//Same Week 
      sum += data.count; 
     } else if([itemComps weekOfYear] >= [currComps weekOfYear] && [itemComps month] == [currComps month] && [itemComps year] == [currComps year]) { //Next Week 

      Stat *stat = [[CSInstallStat alloc] init]; 
      stat.time = [currComps date]; 
      stat.count = sum; 
      stat.timeAccuracy = ENUMWeekly; 
      [weeklyData addObject:stat]; 
      sum = 0; 
      sum += data.count; 
      prev = data; 
     } else { 
      prev = data; 
     } 

    } 
    self.weeklyData = weeklyData; 


} 

Answer 1

如果我正在實施這種制度，我會傾向於維護統計的對象進來，所以，讓我們說我們有「每週數據」數組，並讓我們說清酒我們想要保持52周的價值。在你的類中，聲明成員變量：

NSCalendar *gregorianCalendar; 
unsigned lastItemWeek; 
struct weekinfo { 
    unsigned frequency; 
    unsigned month; 
    int year; 
} weeklyStats[53]; 

當一個新的價值在於，你只是做

- (id)init 
{ 
    if ((self = [super init])) { 
    ... 
    /* Must fix the calendar we're using, or at least understand the one we're 
     using. Using [NSCalendar currentCalendar] is potentially risky as we 
     don't necessarily know what that is. */ 
    gregorianCalendar = [[NSCalendar alloc] 
         initWithCalendarIdentifier:NSGregorianCalendar]; 
    ... 
    } 
} 

- (void)gotNewItemWithDate:(NSDate *)date 
{ 
    NSDateComponents *itemComps = [gregorianCalendar 
           components:(NSWeekOfYearCalendarUnit 
              | NSCalendarUnitMonth | NSCalendarUnitYear) 
           fromDate:date]; 
    unsigned week = [itemComps week] - 1; // This runs from 0 to 52 inclusive 
    unsigned month = [itemComps month]; 
    int year = [itemComps year]; 

    if (week == lastItemWeek) 
    ++weeklyStats[week].frequency; 
    else { 
    // Some years don't have week 53 (which we store in weeklyStats[52]) 
    if (week == 0 && lastItemWeek == 51) 
     weeklyStats[52] = (struct weekinfo){ 0, 0, 0 }; 

    weeklyStats[week] = (struct weekinfo){ 1, month, year }; 
    } 
    lastItemWeek = week; 
} 

你可以存儲在Stat對象，而不是如果你真的想要，但似乎有點不必要。

同樣顯而易見的是，您可以擴展這種方法來維護日常統計數據等。

兩個警告：

1. 周是棘手;有些年份有53周，有些有52年。因此，weeklyStats[52]可能有效或不可能有效。如果我們在第52周的最後一週，我選擇在此清除它。

2. weeklyStats[lastItemWeek]給出的元素不是最終值。