字典数组中每个对象的最大值

Question

我有一个字典数组，我正在尝试获取数组中每个玩家的最高分数。每个玩家都可以有多个条目我正在尝试获取每个玩家最佳成绩的字典数组。

NS数组 [0] - NSDictionary

        - [0] Score: (double)20.7
        - [1] NameID: (int) 1
        - [2] Date

[1] - NSDictionary

        - [0] Score: (double)25
        - [1] NameID: (int) 1
        - [2] Date

[2] - NSDictionary

        - [0] Score: (double)28
        - [1] NameID: (int) 2
        - [2] Date

[3] - NSDictionary`

        - [0] Score: (double)26
        - [1] NameID: (int) 3
        - [2] Date

我试过使用 NSPredicate predicateWithFormat，但我只能取回数组中与名称无关的所有内容的最大值。

预期输出：

NS数组 [1] - NSDictionary

        - [0] Score: (double)25
        - [1] NameID: (int) 1
        - [2] Date

[2] - NSDictionary

        - [0] Score: (double)28
        - [1] NameID: (int) 2
        - [2] Date

[3] - NSDictionary`

        - [0] Score: (double)26
        - [1] NameID: (int) 3
        - [2] Date

感谢您的帮助。

Answer 1

您不能为此使用 NSPredicate，因为您要确定多个不同玩家的最高得分。在幕后，NSPredicate 无论如何都会迭代数组，因此使用您自己的循环并不会降低效率。在下面的代码中，我假设分数和玩家姓名包含在 NSNumber

中

-(NSArray *)maxScoresForPlayers:(NSArray *)playerScores {

    NSMutableDictionary *maxScores = [NSMutableDictionary new];

    for (NSDictionary *player in playerScores) {
        NSNumber *playerID = (NSNumber *)player[@"NameID"];
        NSDictionary *playerMax = maxScores[playerID];
        if (playerMax == nil) {
           playerMax = player;
        } else {
           NSNumber *currentMax = (NSNumber *)[playerMax[@"Score"];
           NSNumber *playerScore = (NSNumber *)player[@"Score"];
           if ([playerScore doubleValue] > [currentMax doubleValue]) {
                playerMax = player;
           }
        }
        maxScores[playerID] = playerMax;
    }

    return([maxScores allValues];
}

Answer 2

您可以像这样手动完成：

NSMutableDictionary *maxScoresDict = [NSMutableDictionary dictionary];
for (NSDictionary *score in scoresArray) {
    NSNumber *key = score[@"NameID"];
    NSNumber *savedMax = maxScoresDict[key][@"Score"];
    NSNumber *currentMax = maxScoresDict[key][@"Score"];
    if (savedMax == nil || [currentMax doubleValue] > [savedMax doubleValue]) {
        maxScoresDict[key] = score;
    }
}
NSArray *maxScoresArray = [maxScoresDict allValues];

Answer 3

您需要做的是找到每个用户的分数，然后从中找出最高分数。

- (void)findMaxScoreForUser:(int)userId {

NSDictionary *dict0 = [NSDictionary dictionaryWithObjects:@[@27.0,@3] forKeys:@[@"Score",@"UserID"]];
NSDictionary *dict1 = [NSDictionary dictionaryWithObjects:@[@25.0,@2] forKeys:@[@"Score",@"UserID"]];
NSDictionary *dict2 = [NSDictionary dictionaryWithObjects:@[@23.0,@3] forKeys:@[@"Score",@"UserID"]];

NSArray *arr = [NSArray arrayWithObjects:dict0,dict1,dict2, nil];
NSMutableArray *scores = [NSMutableArray array];
for (NSDictionary *dict in arr) {
    int userID = [[dict valueForKey:@"UserID"] intValue];
    if (userId == userID) {
        [scores addObject:[dict valueForKey:@"Score"]];
    }
}

int max = [[scores valueForKeyPath:@"@max.intValue"] intValue];

}

Answer 4

试试这个：

NSArray *objects = @[@{@"Score": @(20.7),
                       @"NameID": @(1),
                       @"Date": [NSDate date]},
                     @{@"Score": @(25),
                       @"NameID": @(1),
                       @"Date": [NSDate date]},
                     @{@"Score": @(28),
                       @"NameID": @(2),
                       @"Date": [NSDate date]},
                     @{@"Score": @(26),
                       @"NameID": @(3),
                       @"Date": [NSDate date]}];
NSMutableArray *users = [NSMutableArray array];

for (NSInteger i=0; i<objects.count; i++) {

    NSDictionary *dict = objects[i];
    NSNumber *nameID = dict[@"NameID"];

    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"self.NameID==%@", nameID];
    NSInteger index = [users indexOfObjectPassingTest:^BOOL(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
        BOOL found = [predicate evaluateWithObject:obj];
        return found;
    }];

    if (index != NSNotFound) {
        NSNumber *score1 = dict[@"Score"];
        NSNumber *score2 = users[index][@"Score"];

        if (score1.doubleValue > score2.doubleValue) {
            [users replaceObjectAtIndex:index withObject:dict];
        }
    }
    else {
        [users addObject:dict];
    }
}
NSLog(@"%@", users);

Answer 5

- (NSArray *)getBestScores:(NSArray *)players {
    NSMutableDictionary *best = [[NSMutableDictionary alloc] init];
    for (NSDictionary *p in players) {
        NSDictionary *b = [best valueForKey:[p valueForKey:@"NameID"]];
        if (!b || [[p valueForKey:@"Score"] doubleValue] > [[b valueForKey:@"Score"] doubleValue])
            [best setValue:p forKey:[p valueForKey:@"NameID"]];
    }
    return [best allValues];
}

Answer 6

// Get Max Value of integer element from Array of Dictonaries.
// Example Array Starts

<paramArray>(
{
DicID = 1;
Name = "ABC";
ValuetoCalculateMax = 2800;
},
{
DicID = 2;
Name = "DEF";
ValuetoCalculateMax = 2801;
},
{
DicID = 3;
Name = "GHI";
ValuetoCalculateMax = 2805;
}
)
// Example Array Ends

// Implementation


int   MaxintegerValue=0;

MaxintegerValue=[self getMaxValueFromArrayofDictonaries:paramArray];

// Implementation Ends


// Function Starts

-(int)getMaxValueFromArrayofDictonaries:(NSArray *)paramArray
{
int MaxValue=0;
NSMutableDictionary  *dic=[[NSMutableDictionary alloc]init];
for ( int i=0; i<[paramArray count]; i++ )
{
    dic=[paramArray objectAtIndex:i];
    if ([[dic valueForKey:@"ValuetoCalculateMax"] intValue] > MaxValue)
    {
        MaxValue=[[dic valueForKey:@"ValuetoCalculateMax"] intValue];
    }
    else
    {
        MaxValue=MaxValue;
    }
    }
   return MaxValue;
}

// Function Ends

字典数组中每个对象的最大值

Max value for each object in an Array of Dictionaries

arrays

dictionary

objective-c

nspredicate

ios