iOS统计数组相同元素的个数

ゝ一纸荒年。 2022-07-12 12:34 275阅读 0赞

- (void)viewDidLoad {
        [super viewDidLoad];
        
        //统计数组相同元素的个数
        
        NSMutableDictionary *dic = [[NSMutableDictionary alloc] init];
        //需要统计的数组
        NSMutableArray *array = [[NSMutableArray alloc]initWithObjects:@"1",@"2",@"3",@"3",@"3",@"3", nil];
        NSSet *set = [NSSet setWithArray:array];
        for (NSString *setstring in set) {
            //需要去掉的元素数组
            NSMutableArray *filteredArray = [[NSMutableArray alloc]initWithObjects:setstring, nil];
            NSMutableArray *dataArray = array;
            NSPredicate * filterPredicate = [NSPredicate predicateWithFormat:@"NOT (SELF IN %@)",filteredArray];
            //过滤数组
            NSArray * reslutFilteredArray = [dataArray filteredArrayUsingPredicate:filterPredicate];
            //NSLog(@"Reslut Filtered Array = %@",reslutFilteredArray);
            int number = (int)(dataArray.count-reslutFilteredArray.count);
            //NSLog(@"number :%d",number);
            [dic setObject:[NSString stringWithFormat:@"%d",number] forKey:setstring];
        }
        NSLog(@"dic :%@",dic);
        
    }

- (void)viewDidLoad {
        [super viewDidLoad];
        
        //参考数组筛选：
        
        //需要去掉的元素数组
        NSMutableArray *filteredArray = [[NSMutableArray alloc]initWithObjects:@"1",@"4", nil];
        //需要被筛选的数组
        NSMutableArray *dataArray = [[NSMutableArray alloc]initWithObjects:@"1",@"2",@"1",@"4",@"6",@"1",@"1",@"4",@"1",@"6",@"4", nil];
        
        /*
         方法一：利用NSPredicate
         注：NSPredicate所属Cocoa框架，在密码、用户名等正则判断中经常用到。
         类似于SQL语句
         NOT 不是
         SELF 代表字符串本身
         IN 范围运算符
         那么NOT (SELF IN %@) 意思就是：不是这里所指定的字符串的值
         */
        NSPredicate * filterPredicate = [NSPredicate predicateWithFormat:@"NOT (SELF IN %@)",filteredArray];
        //过滤数组
        NSArray * reslutFilteredArray = [dataArray filteredArrayUsingPredicate:filterPredicate];
        NSLog(@"Reslut Filtered Array = %@",reslutFilteredArray);
        /*
         结果：
         Reslut Filtered Array = (
         2,
         6,
         6
         )
         */
        
        /*
         方法二：从后往前遍历数组，然后匹配删除
         */
        int i = (int)[dataArray count]-1;
        for(;i >= 0;i --){
            //containsObject 判断元素是否存在于数组中(根据两者的内存地址判断，相同：YES  不同：NO）
            if([filteredArray containsObject:[dataArray objectAtIndex:i]]) {
                [dataArray removeObjectAtIndex:i];
            }
        }
        NSLog(@"Data Array = %@",dataArray);
        /*
         结果：
         Data Array = (
         2,
         6,
         6
         )
         */
        
    }

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