16

I am trying to get the sum of the value from list of list using linq ?my data is as below code 

        List<List<string>> allData = new List<List<string>>();
        using (StreamReader reader = new StreamReader(path))
        {
            while (!reader.EndOfStream)
            {
                List<string> dataList;
                dataList = reader.ReadLine().Split('|').ToList();
                allData.Add(dataList);
            }
        }

which gives me data in allData as below 

           allData-->[0]-->[0]-'name1'
                           [1]-'sub'
                           [2]-'12'
                     [1]-->[0]-'name2'
                           [1]-'sub'
                           [2]-'15'  
                     [2]-->[0]-'name1'
                           [1]-'sub2'
                           [2]-'15'
    //and so on ....

i have applied group by that gives me grouping by the name but i am not able to figure out how to get the sum of the marks for each name ?

      var grouped = allData.GroupBy(x => x[0]);

after this i get all matching name grouped into one but now how to get sum of the marks for that group ? any help would be great ?

  Output should be  name1=27 and name2=15 and so on.
Improve this question
2
  • Is the number to be added always the third element of each list? Commented Feb 28, 2014 at 5:09
  • @BrianSnow Yes it will always be third element Commented Feb 28, 2014 at 5:13

4 Answers 4

Reset to default
29

Not sure if you want to get the sum of every group or the total. If it's the total then this should do the trick

var sum = allData.Sum(x => Int32.Parse(x[2]));

If it's per key then try the following

var all = allData
  .GroupBy(x => x[0])
  .Select(x => x.Sum(y => Int32.Parse(y[2]));
Improve this answer
Sign up to request clarification or add additional context in comments.

Comments

9 
var grouped = allData.GroupBy(x => x[0])
                     .Select(g => new
                     {
                         Name = g.Key,
                         Sum = g.Sum(x => int.Parse(x[2]))
                     });

It will return an anonymous type instance for each group, with two properties: Name with your grouping key and Sum with sum of marks.

Improve this answer

Comments

1

Sticking as much as possible to the LINQ query language:

var grouped = from d in allData
              group d by i[0] into g
              select new
              {
                  Name = g.Key,
                  Sum = g.Sum(i => int.Parse(i[2]))
              };
Improve this answer

Comments

0

This will give you parallel List with each name and the count of how many times each name occurs.

    var names = grouped.Select(s => s.Key).ToList();
    var nameCount = grouped.Select(s => s.Count()).ToList();

Also... you may want to add this when assigning alldata to grouped. I use this to get a List from greatest to least amount of occurrences.

    var grouped = allData.GroupBy(x => x[0]).OrderByDescending(i => i.Count());
Improve this answer

2 Comments

i dont want the name count if you look at the question i want the sum of third element from inner list.
oh, sorry. I was confused by the "Output" line..... it says "Output should be name1-27 and name=15 and so on..." --> should it be: "Output should be name1 = 27 and name2 = 15 and so on..."..... Either way I learned something new, that was a unique question and those are some great solutions to your problem!

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.