Solved

List<> split in 2

Posted on 2009-05-12
8
353 Views
Last Modified: 2013-12-17
I have a Generic List (List<>).
I want to split it into 2 Lists. In the first one go items which indexnumber is an even number (0,2,4...)
and in the second items which indexnumber is an odd number (1,3,5...).
How is best to do that?
0
Comment
Question by:johnkainn
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 4
  • 4
8 Comments
 
LVL 16

Expert Comment

by:Walter Ritzel
ID: 24366152
The first way I can think of is running thru the list and according to the index, adding in the odd or the even list.
0
 
LVL 22

Expert Comment

by:p_davis
ID: 24366183
List<YourObject> evenResults = mainList.FindAll(x=>x.IndexNumber % 2 == 0 || x.IndexNumber == 0);
List<YourObject> oddResults = mainList.Findall(x=>x.IndexNumber % 2 > 0);

maybe?
0
 
LVL 16

Expert Comment

by:Walter Ritzel
ID: 24366314
The only problem with this approach is that you depend upon using a property from the object inside the list to make the decision.
0
Resolve Critical IT Incidents Fast

If your data, services or processes become compromised, your organization can suffer damage in just minutes and how fast you communicate during a major IT incident is everything. Learn how to immediately identify incidents & best practices to resolve them quickly and effectively.

 
LVL 22

Expert Comment

by:p_davis
ID: 24366357
umm that's what the asker is basing the branching (separate lists) on. unless i am misunderstanding the question/purpose.
0
 
LVL 22

Expert Comment

by:p_davis
ID: 24366369
and why would that be a problem? i am asking seriously b/c i am always willing to learn something new.
0
 
LVL 16

Accepted Solution

by:
Walter Ritzel earned 125 total points
ID: 24366400
This would be the standard way:
<eeSnippet>
    class SimpleObject
    {
        private int id;
        private String name;

        public String Name
        {
            get { return name; }
            set { name = value; }
        }

        public int Id
        {
            get { return id; }
            set { id = value; }
        }

        public SimpleObject(int p_id, String p_name)
        {
            this.id = p_id;
            this.name = p_name;

        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            //Creating and Populating the list
            List<SimpleObject> mainList = new List<SimpleObject>();
            for (int i=0; i < 10; i++)
            {
                mainList.Add(new SimpleObject(i,"name " + i.ToString()));
            }

            //Approach not using LINQ
            List<SimpleObject> oddList = new List<SimpleObject>();
            List<SimpleObject> evenList = new List<SimpleObject>();
            int j = 0;
            foreach(SimpleObject obj in mainList)
            {
                if ((j % 2 == 0) || (j == 0))
                {
                    evenList.Add(obj);
                }
                else
                {
                    oddList.Add(obj);
                }
            }
        }
    }
</eeSnippet>
0
 
LVL 22

Assisted Solution

by:p_davis
p_davis earned 125 total points
ID: 24366411
that effectively does the exact same thing that i posted.
0
 
LVL 16

Expert Comment

by:Walter Ritzel
ID: 24366609
Sure, man. Let me explain: it's become a problem if, for example, your object does not have an IndexNumber or any number property... My solution does not consider the values inside the object, just the position inside the list.
0

Featured Post

Webinar: Aligning, Automating, Winning

Join Dan Russo, Senior Manager of Operations Intelligence, for an in-depth discussion on how Dealertrack, leading provider of integrated digital solutions for the automotive industry, transformed their DevOps processes to increase collaboration and move with greater velocity.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

IP addresses can be stored in a database in any of several ways.  These ways may vary based on the volume of the data.  I was dealing with quite a large amount of data for user authentication purpose, and needed a way to minimize the storage.   …
Recently while returning home from work my wife (another .NET developer) was murmuring something. On further poking she said that she has been assigned a task where she has to serialize and deserialize objects and she is afraid of serialization. Wha…
Attackers love to prey on accounts that have privileges. Reducing privileged accounts and protecting privileged accounts therefore is paramount. Users, groups, and service accounts need to be protected to help protect the entire Active Directory …
This video shows how to use Hyena, from SystemTools Software, to update 100 user accounts from an external text file. View in 1080p for best video quality.

752 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question