Sorting Map<Integer,List<Double>>

Question

Based on Map<Integer,List<Double>> dist , I should create int[][] indexes that will store sorted indexes in ascending order, eg:

dist = 
0, [2.5, 3.5, 8.4]
1, [1.0, 5.0, 6.2]

int[][] indexes =
1,0                  // refers to 1.0 in dist, because it's a smallest value
0,0,                 // refers to 2.5 in dist
0,1,
1,1,
1,2
0,2                  // refers to 8.4 in dist

Any idea how to do this? Thanks.

Answer 1

you can create a reverse map of TreeMap<Double,List<IndexClass>> .

 class IndexClass {
       public int row;
       public int column;
 }

And the sorting function is like this:

 public List<IndexClass> sort(Map<Integer,List<Double>> dist) {
      //Use TreeMap because it will auto sort keys
      TreeMap<Double,List<IndexClass>> treeMap = new TreeMap<Double,List<IndexClass>>();
      for (Map.Entry<Integer, List<Double>> entry : dist.entrySet()) {
           List<Double> distValues = entry.getValue();
           for (int i = 0; i < distValues.size(); i++) {
                Double value = distValues.get(i);
                IndexClass index = new IndexClass();
                index.row = entry.getKey();
                index.column = i;
                //There is a duplicate value, simple add the index into the list
                if (treeMap.contains(value) {
                     treeMap.get(value).add(index);
                //It is a new value, so create a list instead
                } else {
                     List<IndexClass> indexList = new ArrayList<IndexClass>();
                     indexList.add(index);
                     treeMap.put(value, indexList.add);
                }
           }
      }
      List<IndexClass> finalList = new ArrayList<IndexClass>();
      //Add all list items together
      for (Map.Entry<Double,List<IndexClass>> entry : treeMap.entrySet()) {
           finalList.addAll(entry.getValue());
      }     
      return finalList;
 }

And then you loop through dist and put them into the treeMap.

Then you can print out the values of the treeMap.

Answer 2

Could It be possible.

1. Iterate through structure dist,

2. Create a List of RankedEntry.

   public class RankedEntry implements Comparable{ Double value; int rowIdx; int colIdx;

     public RankedEntry(Double value, int rowIdx, int colIdx) { this.value = value; this.rowIdx = rowIdx; this.colIdx = colIdx; } @Override public int compareTo(Object o) { return this.value.compareTo((Double)o); } } 

3. You do not have a sorted list in java but you can use Collections sorting methods.

4. Then you can iterate through the This list it will give you structure.

5. Fetch rowIdx and colIdx and put them in int[][] indexes