Nested Group in LINQ

In this blog you will learn how to solve a problem where multiple grouping in data source was required. Sharing the problem statement and code snippet.

Suppose, We have following data source:


Now, I want to basically group these users and show the count of browser type they are using. Thus, my output should look like:

Solution:

We need to first group the data by UserIds, and from that result-set we need to again group by individual browser names (excluding their version numbers). Here is the complete code snippet:

using System;
using System.Collections.Generic;
using System.Linq;

public class Program
{
    public static void Main()
    {
         List<BrowserInfo> browesers = new List<BrowserInfo>
            {
                new BrowserInfo { UserID = 1, Browser = "Chrome-32.0"},
                new BrowserInfo { UserID = 1, Browser = "Chrome-30.0"},
                new BrowserInfo { UserID = 1, Browser = "Chrome-33.0"},
                new BrowserInfo { UserID = 1, Browser = "Firefox-20.0"},
                new BrowserInfo { UserID = 1, Browser = "Firefox-26.0"},
                new BrowserInfo { UserID = 1, Browser = "Safari"},
                new BrowserInfo { UserID = 1, Browser = "IE 9"},
                new BrowserInfo { UserID = 1, Browser = "IE 10"},
                new BrowserInfo { UserID = 2, Browser = "Chrome-31.0"},
                new BrowserInfo { UserID = 2, Browser = "Chrome-32.0"},
                new BrowserInfo { UserID = 2, Browser = "IE 10"},
                new BrowserInfo { UserID = 2, Browser = "Firefox-22.0"},
                new BrowserInfo { UserID = 2, Browser = "Firefox-20.0"}
            };


            var query = from browser in browesers
            group browser by browser.UserID into UserGroup
            from countGroup in
            from brow in UserGroup
            group brow by new
            {
                  Chrome = brow.Browser.Contains("Chrome"),
                  Firefox = brow.Browser.Contains("Firefox"),
                  IE = brow.Browser.Contains("IE")
             } into g
             select new
             {
                   ChromeCount = g.Key.Chrome ? g.Count() : 0,
                   FirefoxCount = g.Key.Firefox ? g.Count() : 0,
                   IECount = g.Key.IE ? g.Count() : 0,
                   OthersCount = (!g.Key.Chrome && !g.Key.Firefox && !g.Key.IE) ? g.Count() : 0
             }
             )
             group countGroup by UserGroup.Key;

            Console.WriteLine("UserId | Chrome | Firefox | IE | Others");
            Console.WriteLine("----------------------------------------");
            foreach(var users in query)
            {
                Console.WriteLine("{0} | {1} | {2} | {3} | {4} ",
                users.Key, users.Where(x => x.ChromeCount != 0).Select(x => x.ChromeCount).FirstOrDefault(),
                users.Where(x => x.FirefoxCount != 0).Select(x => x.FirefoxCount).FirstOrDefault(),
                users.Where(x => x.IECount != 0).Select(x => x.IECount).FirstOrDefault(),
                users.Where(x => x.OthersCount != 0).Select(x => x.OthersCount).FirstOrDefault()
                        );
            }

    }
}

public class BrowserInfo
{
      public int UserID { get; set; }
      public string Browser { get; set; }
}

Final Output