Question

我想通过它的objets对数组进行排序，然后得到如下的索引：

NSMutableArray *myArray = [[NSMutableArray alloc] initWithObjects: @"3", @"2", @"1", @"0", @"1", @"2", nil];

我希望对象的索引按升序排列。在这里，因为最低值的索引为3，所以索引将是：3,2,4,1,5,0或类似的东西。

有什么想法吗？

谢谢！

Answer 1

这是我最终做的事情：

//Create a mutable array of the indexes in the myArray (just a list from 0...n)

NSMutableArray *indexes = [[NSMutableArray alloc] init];

for (int i = 0; i < myArray.count; i++){
    [indexes addObject: [NSNumber numberWithInteger:i]];
}

//Create a dictionary with myArray as the objects and the indexes as the keys
NSDictionary *tempDictionary = [NSDictionary dictionaryWithObjects:myArray forKeys:indexes];

//Create an array of myArray's keys, in the order they would be in if they were sorted by the values 
NSArray *sorted = [tempDictionary keysSortedByValueUsingSelector: @selector(compare:)];

Answer 2

只需对其进行排序并使用indexOfObject:即可。像这样：

NSArray *sorted = [myArray sortedArrayUsingSelector: @selector(compare:)];
NSMutableArray *indices = [NSMutableArray array];
for (id object in myArray)
  [indices addObject: [NSNumber numberWithInteger: [sorted indexOfObject: object]]];

（出于我的想法，希望这有效。）

Answer 3

您也可以使用下面的代码，可能对您有用，

    NSSortDescriptor *_lastDescriptor = [[NSSortDescriptor alloc] initWithKey:@"" ascending:YES];
NSArray *_lastArray = [NSArray arrayWithObject:_lastDescriptor];


firstCharacterArray = (NSMutableArray *)[[nameIndexesDictionary allKeys] sortedArrayUsingDescriptors:_lastArray];
//firstCharacterArray = (NSMutableArray *)[[nameIndexesDictionary allKeys] sortedArrayUsingSelector:@selector(localizedCaseInsensitiveCompare:)];
for (NSString *eachlastIndex in firstCharacterArray)
{
    NSSortDescriptor *lastDescriptor = [[NSSortDescriptor alloc] initWithKey:@""
                                                                   ascending:YES];
    //selector:@selector(localizedCaseInsensitiveCompare:)] ;
    NSArray *descriptorslast = [NSArray arrayWithObject:lastDescriptor];
    [[nameIndexesDictionary objectForKey:eachlastIndex] sortUsingDescriptors:descriptorslast];
    [lastDescriptor release];
}

如何从另一个已排序的数组中获取索引数组？

3 个答案: