c# - Summarizing duplicate rows in datatable -

i have table , want sum duplicate rows:

|name  | n |   |name  | n | |------+---|   |------+---| |leo   | 1 |   |leo   | 3 | |wayne | 1 |   |wayne | 2 | |joe   | 1 |   |joe   | 1 | |wayne | 1 | |leo   | 1 | |leo   | 1 | 

i can delete this, how summarize?

        arraylist uniquerecords = new arraylist();         arraylist duplicaterecords = new arraylist();          foreach (datarow drow in table.rows)         {             if (uniquerecords.contains(drow["name"]))                 duplicaterecords.add(drow);             else                 uniquerecords.add(drow["name"]);         }          foreach (datarow drow in duplicaterecords)         {             table.rows.remove(drow);         } 

this how dictionary. create dictionary "name" datarow object , sum datarows' "n" property:

// create intermediate dictionary group records dictionary<string, datarow> summarizedrecords = new dictionary<string, datarow>();  // iterate on records  foreach(datarow drow in table.rows) {   // if record in dictionary -> sum "n" value   if(summarizedrecords.containskey(drow["name"]))   {     summarizedrecords[drow["name"]].n += drow["n"];   }   else   {     // otherwise add element     summarizedrecords[drow["name"]] = drow;   } }  // transform dictionary list further usage arraylist<datarow> summarizedlist = summarizedrecords.values.tolist(); 

i think can done more elegantly (1 line of code) linq. let me think more :)

edit

here linq version, involves creating new datarow objects, may not intention - don't know:

arraylist<datarow> summarizedrecords = table.rows.groupby(row => row["name"]) // line groups records "name"               .select(group =>                        {                         int sum = group.sum(item => item["n"]);  // line sums "n"'s of group                         datarow newrow = new datarow();  // create new datarow object                         newrow["name"] = group.key;      // set "name" (key of group)                         newrow["n"] = sum;               // set "n" sum                         return newrow;                   // return new datarow                       })               .tolist();     // make resulting enumerable list