I have two lists of object:
Customer And Employee
I need to check if there is at least 1 Client with the same name as an employee.
Currently I have:
client.ForEach(a =>
{
if (employee.Any(m => m.Name == a.Name && m.FirstName==a.FirstName)
{
// OK TRUE
}
});
can I improve reading by doing it in another way?
why won't you check it before hand using join?
var mergedClients = Client.Join(listSFull,
x => new { x.Name, x.FirstName},
y => new { Name = y.Name, FirstName= y.FirstName},
(x, y) => new { x, y }).ToList();
and then iterate over the new collection:
mergedClients.ForEach(a =>
//your logic
Only disadvantage of this approach (if it bothers you) is that null values will not be included.
I would go either with Join
var isDuplicated = clients.Join(employees,
c => new { c.Name, c.FirstName },
e => new { e.Name, e.FirstName },
(c, e) => new { c, e })
.Any();
or Intersect
var clientNames = clients.Select(c => new { c.Name, c.FirstName });
var employeeNames = employees.Select(e => new { e.Name, e.FirstName });
var isDuplicated = clientNames.Intersect(employeeNames).Any();
Both of Join and Intersect use hashing, and are close to O(n).
Note: equality (and hash code) of anonymous objects (new { , }) is evaluated as for a value type. I.e. two anonymous objects are equal (implies have same hash code) when all their fields are equal.
=== EDIT: Ok, I was interested myself (hope your question was about performance :P)
[TestMethod]
public void PerformanceTest()
{
var random = new Random();
var clients = Enumerable.Range(0, 10000)
.Select(_ => new Person { FirstName = $"{random.Next()}",
LastName = $"{random.Next()}" })
.ToList();
var employees = Enumerable.Range(0, 10000)
.Select(_ => new Person { FirstName = $"{random.Next()}",
LastName = $"{random.Next()}" })
.ToList();
var joinElapsedMs = MeasureAverageElapsedMs(() =>
{
var isDuplicated = clients.Join(employees,
c => new { c.FirstName, c.LastName },
e => new { e.FirstName, e.LastName },
(c, e) => new { c, e })
.Any();
});
var intersectElapsedMs = MeasureAverageElapsedMs(() =>
{
var clientNames = clients.Select(c => new { c.FirstName, c.LastName });
var employeeNames = employees.Select(e => new { e.FirstName, e.LastName });
var isDuplicated = clientNames.Intersect(employeeNames).Any();
});
var anyAnyElapsedMs = MeasureAverageElapsedMs(() =>
{
var isDuplicated = clients.Any(c => employees.Any(
e => c.FirstName == e.FirstName && c.LastName == e.LastName));
});
Console.WriteLine($"{nameof(joinElapsedMs)}: {joinElapsedMs}");
Console.WriteLine($"{nameof(intersectElapsedMs)}: {intersectElapsedMs}");
Console.WriteLine($"{nameof(anyAnyElapsedMs)}: {anyAnyElapsedMs}");
}
private static double MeasureAverageElapsedMs(Action action) =>
Enumerable.Range(0, 10).Select(_ => MeasureElapsedMs(action)).Average();
private static long MeasureElapsedMs(Action action)
{
var stopWatch = Stopwatch.StartNew();
action();
return stopWatch.ElapsedMilliseconds;
}
public class Person
{
public string FirstName { get; set; }
public string LastName { get; set; }
}
Output:
joinElapsedMs: 5.9
intersectElapsedMs: 3.5
anyAnyElapsedMs: 3185.8
Note: any-any is O(n^2) - (in worst case) every employee is iterated per each iterated client.
Related
I have a complex LINQ Query to extract Top students in my university. Here is the query :
var query = Db.Students.AsNoTracking().Where(...).AsQueryable();
var resultgroup = query.GroupBy(st => new
{
st.Student.CourseStudyId,
st.Student.EntranceTermId,
st.Student.StudyingModeId,
st.Student.StudyLevelId
}, (key, g) => new
{
CourseStudyId = key.CourseStudyId,
EntranceTermId = key.EntranceTermId,
StudyingModeId = key.StudyingModeId,
StudyLevelId = key.StudyLevelId,
list = g.OrderByDescending(x =>
x.StudentTermSummary.TotalAverageTillTerm).Take(topStudentNumber)
}).SelectMany(q => q.list).AsQueryable();
This Query give me top n students based on 4 parameters and on their TotalAverageTillTerm.
Now I want to add rownum for each group to simulate Total rank, for example Output is :
Now I want to Add TotalRank as rownumber like Sql. In the picture X1=1,X2=2,X3=3 and Y1=1,Y2=2,Y3=3
If I want to reduce problem. I only work on one group. Code Like this :
resultgroup = query.GroupBy(st => new
{
st.Student.StudyLevelId
}, st => st, (key, g) => new
{
StudyLevelId = key.StudyLevelId,
list = g.OrderByDescending(x =>
x.StudentTermSummary.TotalAverageTillTerm)
.Take(topStudentNumber)
}).SelectMany(q => q.list).AsQueryable();
list was a List of student but I see no sign of student having a rank property so I wrapped it into a annonimous type with rank.
var query = Db.Students.AsNoTracking().Where(...).AsEnumerable();
var resultgroup = query.GroupBy(st => new {
st.Student.CourseStudyId,
st.Student.EntranceTermId,
st.Student.StudyingModeId,
st.Student.StudyLevelId
})
.SelectMany( g =>
g.OrderByDescending(x =>x.StudentTermSummary.TotalAverageTillTerm)
.Take(topStudentNumber)
.Select((x,i) => new {
CourseStudyId = g.Key.CourseStudyId,
EntranceTermId = g.Key.EntranceTermId,
StudyingModeId = g.Key.StudyingModeId,
StudyLevelId = g.Key.StudyLevelId,
Rank = i+1
//studentPorperty = x.Prop1,
})
)
.AsQueryable();
Do you mean :
var query = Db.Students.AsNoTracking().Where(...).AsQueryable();
var resultgroup = query.GroupBy(st => new
{
st.Student.CourseStudyId,
st.Student.EntranceTermId,
st.Student.StudyingModeId,
st.Student.StudyLevelId
}, (key, g) => new
{
CourseStudyId = key.CourseStudyId,
EntranceTermId = key.EntranceTermId,
StudyingModeId = key.StudyingModeId,
StudyLevelId = key.StudyLevelId,
list = g.OrderByDescending(x =>
x.StudentTermSummary.TotalAverageTillTerm)
.Take(topStudentNumber)
.Select((x, i) => new { Item = x, TotalRank = i /* item number inside group */}),
StudentsInGroupCount = g.Count() // count group this items
}).SelectMany(q => q).AsQueryable();
To see the results :
foreach (var item in resultgroup.ToList())
{
item.list.ForEach(s => Console.WriteLine(s.TotalRank));
}
How do I create groups and subgroup1 and subgroup2 Use linq.
Example of this picture
I want to create json.
Example of this picture.
I tried to do this but there was a problem.
The items are repeated within one subgroup2.
var list = result
.GroupBy(x => new { x.GroupId, x.GroupName })
.Select(g => new
{
ID = g.Key.GroupId,
Name = g.Key.GroupName,
SubGroup1 = g.GroupBy(x => new { x.SubGroupID1, x.SubGroupName1 })
.Select(cg => new
{
ID = cg.Key.SubGroupID1,
Name = cg.Key.SubGroupName1,
SubGroup2 = g.GroupBy(x => new { x.SubGroupID2, x.SubGroupName2 })
.Select(ii => new
{
ID = ii.Key.SubGroupID2,
Name = ii.Key.SubGroupName2,
item = ii.GroupBy(x => new { x.Stock_Id, x.Stock_Name, x.Prices, x.ScreenNumber })
.Select(oo => new
{
Stock_Id = oo.Key.Stock_Id,
Stock_Name = oo.Key.Stock_Name,
Prices = oo.Key.Prices,
ScreenNumber = oo.Key.ScreenNumber
}).OrderBy(Or => Or.Stock_Id)
.ToList()
}).OrderBy(Or => Or.ID)
.ToList()
}).OrderBy(Or => Or.ID)
.ToList()
}).OrderBy(Or => Or.ID)
.ToList();
Your query could be a lot cleaner if you grouped the groups up front, then project out to your desired results.
var query =
from x in data
group new { x.StockId, x.StockName, x.Prices, x.ScreenNumber }
by new { x.GroupId, x.GroupName, x.SubGroupId1, x.SubGroupName1, x.SubGroupId2, x.SubGroupName2 }
into g
group g
by new { g.Key.GroupId, g.Key.GroupName, g.Key.SubGroupId1, g.Key.SubGroupName1 }
into g2
group g2
by new { g2.Key.GroupId, g2.Key.GroupName }
into g1
select new
{
Id = g1.Key.GroupId,
Name = g1.Key.GroupName,
SubGroup1 = g1.Select(g2 => new
{
Id = g2.Key.SubGroupId1,
Name = g2.Key.SubGroupName1,
SubGroup2 = g2.Select(g => new
{
Id = g.Key.SubGroupId2,
Name = g.Key.SubGroupName2,
Items = g.Select(x => new
{
x.StockId,
x.StockName,
x.Prices,
x.ScreenNumber,
}),
}),
}),
};
The idea is to start off with the most specific grouping first, then one-by-one group the groups by the next layer, and so on.
SubGroup2 = g.GroupBy(x => new { x.SubGroupID2, x.SubGroupName2 })
You are grouping g instead of cg.
I suggest structuring your code a bit, which would help avoiding this kind of mistake.
I've been searching for a while now. But all the solutions seems to be different than what I expect.
So this is my query in SQL:-
Select * from
(
select Name,Description Descr from CourseTbl
union all
select MainDesc Name,MainDesc Descr from CoursedescTbl
union all
select SubHeading Name,SubDesc Descr from CourseSubDesc
union all
select Name,Descr as Descr from InternTbl
)A where A.Name like '%D%' or A.Descr like '%D%'
I want to execute the above query using LINQ or EF. and return the list in Json format. So I tried many failed attempts and this is one of them:-
public JsonResult SearchDetail()
{
string SearchKey = Request.Form["SearchName"].ToString();
IEnumerable<SearchList> QueryResult;
using (EBContext db = new EBContext())
{
try
{
QueryResult =
(from x in db.Courses
select new { A = x.Name, B = x.Description })
.Concat(from y in db.CourseDesc
select new { A = y.MainHeading, B = y.MainDesc })
.Concat(from z in db.CourseSubDesc
select new { A = z.SubDesc, B = z.SubHeading })
.Concat(from w in db.Interns
select new { A = w.Name, B = w.Descr })
.ToList();
}
catch (Exception ex)
{
return new JsonResult
{
Data = ex.Message,
JsonRequestBehavior = JsonRequestBehavior.AllowGet
};
}
return new JsonResult
{
Data = QueryResult,
JsonRequestBehavior = JsonRequestBehavior.AllowGet
};
}
}
And my SearchList Class is like this:-
public class SearchList
{
public string Name { get; set; }
public string Descr { get; set; }
}
I'm not able to put the where clause in linq query which will search in all table.
I'm getting error when I assign queryresult to my ef query. It says cannot cast to Innumerable.
Thanks in Advance.
Could you explain more on the error you are getting?
Also, have you tried using .Union() in linq?
QueryResult = db.Courses.Select(x=> new { A = x.Name, B= x.Description})
.Union(db.CourseDesc.Select(y=> new {A = y.MainHeading, B = y.MainDesc })
.Union( //so on
.ToList(); //this isn't necessary
Edit: There are two ways to input where clause, either with each search, or at the end:
QueryResult = db.Courses.Where(x=>x.Name == "Name").Select(x=> new { A = x.Name, B= x.Description})
.Union(db.CourseDesc.Where(y=>y.MainHeading == "Name").Select(y=> new {A = y.MainHeading, B = y.MainDesc })
.Union( //so on
.ToList();
Or:
QueryResult = db.Courses.Where(x=>x.Name == "Name").Select(x=> new { A = x.Name, B= x.Description})
.Union(db.CourseDesc.Where(y=>y.MainHeading == "Name").Select(y=> new {A = y.MainHeading, B = y.MainDesc })
.Union( //so on
//Where can go either before or after .ToList
.Where(item=>item.A == "Name")
.ToList();
You did not say what error/exception you are getting. But your QueryResult is of type IEnumerable<SearchList> and you appear to be assigning it an enumerable of anonymous type { A, B }.
Try this:
QueryResult = (from x in db.Courses
select new SearchList { Name = x.Name, Descr = x.Description })
.Concat(...)
.ToList();
Or
QueryResult = db.Courses.Select(x => new SearchList
{ Name = x.Name, Descr = x.Description})
.Concat(...)
.ToList();
UPDATE
Your #2 issue will be fixed if you changed your select to new up a SearchList as I did above, instead of new-ing an anonymous type.
As for your issue #1, you should insert the Where() before your Select():
result1 = db.Courses
.Where(x => x.Name.Contains('D') || x.Description.Contains('D'))
.Select(x => new SearchList { Name = x.Name, Descr = x.Description});
result2 = db.CourseDesc
.Where(y => y.MainHeading.Contains('D') || y.MainDesc.Contains('D'))
.Select(y => new SearchList { Name = y.MainHeading, Descr = y.MainDesc});
result3 = db.CourseSubDesc
.Where(...)
.Select(...);
QueryResult = result1.Concat(result2).Concat(result3).ToList();
Doing Where() as part of the query on each table is important so you do not fetch all records from that table, unlike if you do the Where() after Concat(). Also note that Concat() may throw an ArgumentNullException.
Take the lists Separately and query and concat
check this example
List<string> a = new List<string>() { "a", "b", "c" };
List<string> b = new List<string>() { "ab", "bb", "cb" };
IEnumerable<SearchList> QueryResult =
a.Where(x => x.Contains("a")).Select(x => new SearchList() { Name = x, Descr = x })
.Concat(b.Where(x => x.Contains("a")).Select(x => new SearchList() { Name = x, Descr = x }));
How do I group so that I don't loose the parent identifier.
I have the following
var grouped = mymodel.GroupBy(l => new { l.AddressId })
.Select(g => new
{
AddressId = g.Key.AddressId,
Quotes = g.SelectMany(x => x.Quotes).ToList(),
}).ToList();
this returns
{ AddressId1, [Quote1, Quote2, Quote3...]}
{ AddressId2, [Quote12, Quote5, Quote8...]}
Now I would like to group these by Quote.Code and Quote.Currency, So that Each address has 1 Object-Quote (that is if all 4 quotes belonging to the address have the same Code and Currency). I would like the sum of Currency in that object.
This works, but I can't get how to add Address to this result:
var test = grouped.SelectMany(y => y.Quotes).GroupBy(x => new { x.Code, x.Currency }).Select(g => new
{
test = g.Key.ToString()
});}
this gives compile error, whenever i try to add AddressId to result:
var test1 = grouped.SelectMany(y => y.Quotes, (parent, child) => new { parent.AddressId, child }).GroupBy(x => new { x.Provider, x.Code, x.Currency, x.OriginalCurrency }).Select(g => new
{
test = g.Key.ToString(),
Sum = g.Sum(x => x.Price)
});
compiler error as well:
var test1 = grouped.Select(x => new { x.AddressId, x.Quotes.GroupBy(y => new { y.Provider, y.Code, y.Currency, y.OriginalCurrency }).Select(g => new
{
addr = x.AddressId,
test = g.Key.ToString(),
Sum = g.Sum(q => q.Price)
};
I would do that this way:
var grouped = mymodel.GroupBy(l => new { l.AddressId })
.Select(g => new
{
AddressId = g.Key.AddressId,
QuotesByCode = g.SelectMany(x => x.Quotes)
.GroupBy(x=>x.Code)
.Select(grp=>new
{
Code = grp.Key.Code,
SumOfCurrency=grp.Sum(z=>z.Currency)
}).ToList(),
}).ToList();
var residenceRep =
ctx.ShiftEmployees
.Include(s => s.UserData.NAME)
.Include(s => s.ResidenceShift.shiftName)
.Join(ctx.calc,
sh => new { sh.empNum, sh.dayDate },
o => new { empNum = o.emp_num, dayDate = o.trans_date },
(sh, o) => new { sh, o })
.Where(s => s.sh.recordId == recordId && s.o.day_flag.Contains("R1"))
.OrderBy(r => r.sh.dayDate)
.Select(r => new
{
dayDate = r.sh.dayDate,
empNum = r.sh.empNum,
empName = r.sh.UserData.NAME,
shiftId = r.sh.shiftId,
shiftName = r.sh.ResidenceShift.shiftName,
recordId,
dayState = r.o.day_desc.Split('[', ']')[1]
}).ToList();
I get an exception :
The LINQ expression node type 'ArrayIndex' is not supported in LINQ to
Entities
How i could find an alternative to Split('[', ']')[1] in this query
You must commit the query and do the split after loading the data:
var residenceRep =
ctx.ShiftEmployees
.Include(s => s.UserData.NAME)
.Include(s => s.ResidenceShift.shiftName)
.Join(ctx.calc,
sh => new { sh.empNum, sh.dayDate },
o => new { empNum = o.emp_num, dayDate = o.trans_date },
(sh, o) => new { sh, o })
.Where(s => s.sh.recordId == recordId && s.o.day_flag.Contains("R1"))
.OrderBy(r => r.sh.dayDate)
.Select(r => new
{
dayDate = r.sh.dayDate,
empNum = r.sh.empNum,
empName = r.sh.UserData.NAME,
shiftId = r.sh.shiftId,
shiftName = r.sh.ResidenceShift.shiftName,
recordId = r.sh.recordId,
dayState = r.o.day_desc,
})
.ToList()//Here we commit the query and load data
.Select(x=> {
var parts = x.dayState.Split('[', ']');
return new {
x.dayDate,
x.empNum,
x.empName,
x.shiftId,
x.shiftName,
x.recordId,
dayState = parts.Length > 1 ?parts[1]:"",
};
})
.ToList();
I had this Issue and the approach that I've chose was that get all element I wanted and save them into a List and then filter the actual data on that list.
I know this is not the best answer but it worked for me.