[英]Sort multi dimensional array based on sum of internal arrays in objective c
Let's say I have a multi-dimensional array like this: 假设我有一个像这样的多维数组:
(
(2, 2, 1),
(0, 1, 2),
(0, 1, 1),
(0, 0, 1),
(0, 0, 2),
(0, 1, 3),
(0, 1, 0),
(0, 0, 1),
(0, 0, 1),
(1, 3, 3)
)
Now I need to sort this array in descending order of the internal array's sum. 现在,我需要按照内部数组总和的降序对数组进行排序。
I tried by adding this array and another array of the sum values in a dictionary, but it doesn't work if the sum contains similar numbers. 我尝试通过在字典中添加此数组和总和值的另一个数组,但是如果总和包含相似的数字,它将不起作用。
ie, I want the result to be: 即,我希望结果是:
(1, 3, 3),
(2, 2, 1),
(0, 1, 3),
(0, 1, 2),
(0, 1, 1),
(0, 0, 2),
(0, 0, 1),
(0, 0, 1),
(0, 1, 0)
Any help would be appreciated! 任何帮助,将不胜感激!
Fonix's answer is cool, but it's Swift, In Obj-C then do like this: Fonix的答案很酷,但它是Swift,在Obj-C中执行以下操作:
NSArray *numArray = @[@[@1,@1,@1], @[@0,@0,@0], @[@2,@2,@2], @[@0,@1,@2]];
NSArray *sortedArray;
sortedArray = [numArray sortedArrayUsingComparator:^NSComparisonResult(id a, id b) {
NSNumber *first = [(NSArray *)a valueForKeyPath:@"@sum.self"];
NSNumber *second = [(NSArray *)b valueForKeyPath:@"@sum.self"];
return [first compare:second];
}];
NSLog(@"sorted %@",sortedArray);
something like this should work 这样的事情应该工作
let multiDimenArray = [[0,1,2],[2,3,4],[1,2,3]]
let sorted = multiDimenArray.sort { a, b -> Bool in
let aR = a.reduce(0, combine:+) //sums the numbers inside a
let bR = b.reduce(0, combine:+)
return aR > bR //swap direction of > if you want ascending or descending
}
print(sorted);
prints 版画
[[2, 3, 4], [1, 2, 3], [0, 1, 2]]
edit: 编辑:
doh, brain forgot that it should be in objective-c Doh,大脑忘记了它应该在Objective-C中
You can do that with key-value coding: 您可以使用键值编码做到这一点:
NSArray *array = …; // Whatever you have
NSSortDescriptor *sorter = [NSSortDescriptor sortDescriptorWithKey:@"@sum.self" ascending:NO]; // @sum is an aggregate
NSArray *sorted = [array sortedArrayUsingDescriptors:@[sorter]]);
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