lambda expression join list<object> with list<string>

Question

I have List<object> and List<string> with records. I want inner join both list.

Following is my list with records.

var listContributionDetailsToBeUpdated = new List<ContributionDetailModel> 
{
    new ContributionDetailModel { EmployeeNumber="1", EmployeeFirstName="david", EmployeeLastName="k", NHIPNumber="nhi-100" },
    new ContributionDetailModel { EmployeeNumber="2", EmployeeFirstName="xavior", EmployeeLastName="f",NHIPNumber="nhi-101"},
    new ContributionDetailModel { EmployeeNumber="3", EmployeeFirstName="george", EmployeeLastName="s", NHIPNumber="nhi-102" },
    new ContributionDetailModel { EmployeeNumber="4", EmployeeFirstName="pandit", EmployeeLastName="h",NHIPNumber="nhi-103"},
    new ContributionDetailModel { EmployeeNumber="5", EmployeeFirstName="zania", EmployeeLastName="d", NHIPNumber="nhi-104" }
};

var updatedRecored = new List<string> { "nhi-100", "nhi-101", "nhi-102" };

Can any one help me to inner join both list.

Sergey Berezovskiy · Accepted Answer · 2015-06-01 07:19:13Z

3

It's pretty straight-forward. Just select NHIPNumber from contribution details as key for joining:

var result = from c in listContributionDetailsToBeUpdated
             join r in updatedRecored on c.NHIPNumber equals r
             select c;

Method syntax:

var result = listContributionDetailsToBeUpdated
     .Join(updatedRecored, c => c.NHIPNumber, r => r, (c, r) => c);

You can also use filtering instead of joining, but it's not optimal way, because join is a set operation and it uses internal lookup for joined collection. With simple filtering you will have complexity O(N*M) instead of O(N+M)

var result = listContributionDetailsToBeUpdated
     .Where(c => updatedRecored.Contains(c.NHIPNumber));

edited Jun 1, 2015 at 7:19

answered Jun 1, 2015 at 7:11

Sergey Berezovskiy

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2 Comments

Vijeeshkumar vofox Over a year ago

Can any one help me to get all records Except "updatedRecored".Updated records is var updatedRecored = new List<string> { "nhi-100", "nhi-101", "nhi-102" };

Sergey Berezovskiy Over a year ago

@Vijeeshkumarvofox that should be another question :) simplest solution .Where(c => !updatedRecored.Contains(c.NHIPNumber)). For better performance you can use group join (i.e. join ... into g) and filter by where !g.Any() or use hashset instead of list for npi numbers.

MakePeaceGreatAgain · Accepted Answer · 2015-06-01 07:21:56Z

0

The following may also work:

var result = listContributionDetailsToBeUpdated.Where(x => updatedRecored.Contains(x.NHIPNumber));

answered Jun 1, 2015 at 7:21

MakePeaceGreatAgain

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