Compare lists and get values with Linq?

You can do this by the following Linq statement: var result = List1. Where(x =>! List2.

Select(y => y. Id). Contains(x.Id) || List2.

Single(y => x. Id == y.Id). HourBy.

I created my linq query in my project according to your example It was helped to me. Thanks – fyasar Oct 12 '10 at 8:14.

I think this is what you're after, based on the example lists you supplied... var list3 = new List(); foreach(var item in list1) { var totalFromOther = list2. Where(x => x. Id == item.Id).

Sum(y => y. HourBy); var newItem = new MyClass() { id = item.Id, HourBy = item. HourBy - totalFromOther }; if(newItem.

HourBy > 0) list3. Add(newItem); }.

Here's a solution: var qry = from ee in (from e1 in list1 join e2 in list2 on e1. Id equals e2. Id into gj from e in gj.DefaultIfEmpty() select new { e1.Id, MainHourBy = e1.

HourBy, SecondHourBy = (e == null? 0 : e. HourBy) }) where ee.

SecondHourBy el. SecondHourBy) }.

I use this code, it's not perfect but working and may be clearer for newbie in Linq (like me) List listRes = new List(); foreach ( MyClass item in list1) { var exist = list2 . Select(x => x. MyClass) .

Contains(item); if (!exist) listRes. Add(item); else { var totalFromOther = list2 . Where(x => x.MyClass.Id == item.

Id) . Sum(y => y. HourBy); if (item.

HourBy! = totalFromOther) { item. HourBy = item.

HourBy - totalFromOther; listRes. Add(item); } } } Thanks for you help.

Var agg1 = from l in list1 group l by l. ID into g select new { g. Key, Sum = g.

Sum(_ => _. HourBy) }; var agg2 = from l in list2 group l by l. ID into g select new { g.

Key, Sum = g. Sum(_ => _. HourBy) }; var q = from l1 in agg1 let l2 = agg2.

FirstOrDefault(_ => _. Key == l1. Key) let sum = l1.

Sum - (l2! = null? L2.

Sum : 0) where sum! = 0 select new MyClass(l1. Key, sum); var list3 = q.ToList().

I'm not overly familiar with the 'let' clause. Is it evaluated once for the query, or once per row in this case? – MattH Jul 28 '09 at 12:19.

Group list 2, so there is one entry per ID, with HourBy = total hour by var summedL2 = from item2 in List2 group item2 by item2. ID into g select new Test(g. Key, g.

Sum(item => item. HourBy)); var result = //Select items from list1 from item1 in List1 //Left join to our summed List2 join item2s in summedL2 on item1. ID equals item2s.ID into tempItem2s from item2 in tempItem2s.DefaultIfEmpty() //Where there is no match, or item2 is ID, item1.

HourBy - (item2 == null? 0 : item2. HourBy)).

The following code should do the trick: public List MyExtractionMethod(List List1, List List2) { var results = new List(); // add all the items in List1 that are not in List2 results. AddRange(List1. Where(x =>!

List2. Select(y => y. Id).

Contains(x. Id))); foreach (var item in List2) { var sum1 = List1. Where(c => c.Id == item.

Id). Sum(y => y. HoursBy); var sum2 = List2.

Where(c => c. Id == item.Id). Sum(y => y.

HoursBy); // check for uneven sums and only add the item if it hasn't already been added if (sum1! = sum2 &&!results. Select(x => x.

Id). Contains(item. Id)) { // do not overwrite the existing item in the list, create a new object results.

Add(new MyClass(item.Id, sum1 - sum2)); } } return results; }.

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