Filter map to one row per multiple of ten,based on difference in decreasing order in java

问题

I have a method through which I can filter rows per multiple of ten i.e. I can filter rows which are nearest to multiple of tens such as 10,20,30 etc in ascending order.Now I want to do the same process in decreasing order.

Please refer the following link-Filter array to one row per multiple of ten, based on difference?

In the above mentioned link,the same process is done in ascending order,I want to do this in decreasing order and store the values in map.But I'm not able to do.

I'm using the following code to retrieve rows where beam_current is multiple of ten in a increasing order-

public static  LinkedHashMap<Double, String> ClosestToMultiplesOfTen_User() throws SQLException {

    int row_id ;
    int bIdx = 0;
    double[] vals = new double[34];
   // double[] bucket =new double[bucketCount];
    int rowIndex = 0 ;
    int i=0;

    try
            { 
              con = getConnection();
              stmt = con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_READ_ONLY);
           //   String sql="select logtime,beam_current from INDUS2_BDS.dbo.DCCT where logtime between '"+name+" 00:00:00' and '"+name+" 23:59:59'"+
            //  "and (beam_current like '%9.96' or beam_current like '%9.97' or beam_current like '%9.98' or  beam_current like '%9.99'  or beam_current like '%0' or beam_current like '%_0.01' or beam_current like '%_0.02' or beam_current like '%_0.03' or beam_current like '%_0.04' or beam_current like '%_0.05' or beam_current like '%_0.06') and beam_energy between '550' and '552'";

              String sql="select logtime,beam_current from INDUS2_BDS.dbo.DCCT where logtime between '2014-10-10 08:50:00' and '2014-10-10 12:50:00'"+
                      "and (beam_current like '%9.96' or beam_current like '%9.97' or beam_current like '%9.98' or  beam_current like '%9.99'  or beam_current like '%0' or beam_current like '%_0.01' or beam_current like '%_0.02' or beam_current like '%_0.03' or beam_current like '%_0.04' or beam_current like '%_0.05' or beam_current like '%_0.06')";

              System.out.println("Value of sql of ClosestToMultiplesOfTen_User is"+sql);
              stmt.executeQuery(sql);
              rs = stmt.getResultSet();
       while(rs.next()) 
        {
           for(int j=0; j<1; j++)
             {
               vals[i]  = rs.getDouble(2);
             }
            i++;
         }
        }
     catch( Exception e )
        {
            System.out.println("\nException "+e);
        }
    //  get the max value, and its multiple of ten to get the number of buckets
    double max = java.lang.Double.MIN_VALUE;
    for (double v : vals) max = Math.max(max, v);
    int bucketCount = 1 + (int)(max/10);
    double[] bucket =new double[bucketCount];

    //  initialise the buckets array to store the closest values
   double[][] buckets = new double[bucketCount][3];
 for (int i1 = 0; i1 < bucketCount; i1++){
        // store the current smallest delta in the first element
        buckets[i1][0] = java.lang.Double.MAX_VALUE; 
        // store the current "closest" index in the second element
        buckets[i1][1] = -1d;
        // store the current "closest" value in the third element
        buckets[i1][2] = java.lang.Double.MAX_VALUE;
    }

    //  iterate the rows
    for (row_id=1 ; row_id < vals.length; row_id++)
    {
        //  get the value from the row
        double v = vals[row_id];
        //  get the closest multiple of ten to v
        double mult = getMultipleOfTen(v);
        //  get the absolute distance of v from the multiple of ten
        double delta = Math.abs(mult - v);
        //  get the bucket index based on the value of `mult`
       bIdx = (int)(mult / 10d);
      // System.out.println("value of bidx for bucket index is"+bIdx);
        //    test the last known "smallest delta" for this bucket
        if (buckets[bIdx][0] > delta)
        {
         //  this is closer than the last known "smallest delta"
          buckets[bIdx][0] = delta;
          buckets[bIdx][1] = row_id;
          buckets[bIdx][2] = v;

        }
     }  
   //   print out the result
 for (int i1 =1; i1 <buckets.length; i1++)
   {
         bucket = buckets[i1];
         rowIndex = (int) bucket[1];
         int row_no=rowIndex+1;
         double rowValue = bucket[2];
         System.out.println("row index "+row_no+ "value is "+rowValue);
         DecimalFormat twoDForm = new DecimalFormat("#.##"); 

         rs.absolute(rowIndex);
         user_current_map.put(java.lang.Double.valueOf(twoDForm.format(rs.getDouble(2))),(rs.getString(1)));
        // map1.put(rs.getString(2),(rs.getString(1)));
         //l.add(map1);
     }
System.out.println("user_current_map "+user_current_map);

return user_current_map;
}

public static  double getMultipleOfTen(double v)
{
     System.out.println(10d * Math.round(v / 10d));
    return 10d * Math.round(v / 10d);
}

Now I just want to reverse the order i.e now I want decreasing order of beam_current i.e 210,22,190 etc.

回答1:

To represent it in reverse order do,order by time in your sql query and change the size of buckets to

 for (double v : vals) max = Math.max(max, v);
Arrays.sort(vals);
System.out.println("value at vals[0] c "+vals[0]);
double min=vals[0];
int m2=(int) Math.round(min);
int m3=(int) Math.round(max);

**int bucketCount = 1+((m3-m2)/10);
double[] bucket =new double[bucketCount];
double[][] buckets = new double[bucketCount][3];**

来源：https://stackoverflow.com/questions/29203615/filter-map-to-one-row-per-multiple-of-ten-based-on-difference-in-decreasing-orde

标签

java

linkedhashmap