Sort on two values

Rodney Johnson

I am trying to sort on two values and at this point am not having success. Here is a the code:

        internal DataRow[] SortByCubeDecending(DataTable dr)
        {
            DataTable sortedDR = new DataTable();
            //I am setting the data table that will be returned to the data table I am passing in to not alter the orignial
            sortedDR = dr;
            //This method should sort the datarow array by low weight and high cube for the nose and tail of the trailer
            for (int i = 0; i < dr.Rows.Count; i++)
            {
                for (int j = 1; j < dr.Rows.Count; j++)
                {
                    double cubeOne = (Convert.ToDouble(sortedDR[i][21]) *
                        Convert.ToDouble(sortedDR[i][22]) * Convert.ToDouble(sortedDR[i][23]));
                    double cubeTwo = (Convert.ToDouble(sortedDR[j][21]) *
                        Convert.ToDouble(sortedDR[j][22]) * Convert.ToDouble(sortedDR[j][23]));
                    double weightOne = Convert.ToInt16(sortedDR[i][20]) / Convert.ToInt16(sortedDR[i][19]);
                    double weightTwo = Convert.ToInt16(sortedDR[j][20]) / Convert.ToInt16(sortedDR[j][19]);
                    DataRow temp;
                    if (cubeOne > cubeTwo && weightOne < weightTwo && dr[i]["status"] == false && dr[j]["status"] == false)
                    {
                        temp = sortedDR[i];
                        sortedDR[i] = sortedDR[j];
                        sortedDR[j] = temp;
                    }
                }
            }

            return sortedDR;
        }

My goal is to return a data table sorted by cube (volume) and weight. So for example:
sortedDT[0]["cube"] = 10,000
sortedDT[0]["weight"] = 100
sortedDT[1]["cube"] = 9,000
sortedDT[1]["weight"] = 150
sortedDT[2]["cube"] = 8,500
sortedDT[2]["weight"] = 200
...
sortedDT[n - 10]["cube"] = 2,500 (I do not really care about these in the middle)
sortedDT[n - 10]["weight"] = 2,600
...
sortedDT[n]["cube"] = 1,000
sortedDT[n]["weight"] = 700

Whether I do this with a data table or DataRow[] or an array of structures makes not difference to me. What is most important at this point is I get the extreme values at either end of the sorted tables. I will most likely only be using the top, or bottom, 5 rows then resorting. The "status" column refers to whether or not this row is available. If "status" is true the row is extraneous - already acted upon.

Thank you,

Rod

5 Replies

Know the answer? Post it — somebody with the same question will find it here.

Vulpes15y ago
Accepted answer
It should sort numerically if the column type(s) are double.

For example, if I run this simple example:

DataTable dt = new DataTable();
DataColumn dc = new DataColumn("Number", typeof(double));
dt.Columns.Add(dc);
DataRow dr = dt.NewRow();
dr[0] = 1;
dt.Rows.Add(dr);
DataRow dr2 = dt.NewRow();
dr2[0] = 11;
dt.Rows.Add(dr2);
DataRow dr3 = dt.NewRow();
dr3[0] = 2;
dt.Rows.Add(dr3);
DataView dv = dt.DefaultView;
dv.Sort = "Number";
foreach(DataRowView row in dv) Console.WriteLine(row[0]);

the output is :

1
2
11

and not:

1
11
2
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Rodney Johnson15y ago
Thanks again. I made the addition of typeof(double) to the column declaration and all appears to be well!!!
0
Rodney Johnson15y ago
Vulpes, below is the modified code. I do need to send a data row to the method and from there build a data table with the necessary elements. The data is being sorted, but as if they were strings and not numeric values. What modification can I make to have the data table rows sort as numeric values?

        public void SortByCubeDecending(DataRow[] dr)
        {
            DataTable dt = new DataTable();
            dt.Columns.Add("Track");
            dt.Columns.Add("Cube");
            dt.Columns.Add("Weight");
            for (int i = 0; i < dr.Length; i++)
            {
                DataRow newRow = dt.NewRow();
                newRow["Track"] = dr[i][1];
                newRow["Cube"] = Convert.ToDouble(dr[i][21]) * Convert.ToDouble(dr[i][22]) *
                    Convert.ToDouble(dr[i][23]);
                newRow["Weight"] = Convert.ToDouble(dr[i][20]);
                dt.Rows.Add(newRow);
            }
            DataView view = dt.DefaultView;

            // By default, the first column sorted ascending.
            view.Sort = "Cube, Weight DESC";

        }
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Rodney Johnson15y ago
Thank you. I will give it a try and let you know.

Regards,
0
Vulpes15y ago
Why don't you just create a DataView from your DataTable and then sort that on two columns:

http://msdn.microsoft.com/en-us/library/system.data.dataview.sort.aspx
0