Random Unique Numbers in C#

[cotton31]

Hi All,

I have a list of records which each have an ID. I need to add a random selection of these into an array. The size of the selection is determined by 5% of the total amount of records.

I've managed to do this by generating a random number between 1 and the total amount of records, but I'm struggling to make sure each value is unique.

Is there a better way of doing this?

Thanks,

 

[cotton31]

The first one sounds ideal - how would I do this (the random order part)?

 

[cotton31]

My current set size is around 200 records, and will always be around this size. My subset is 5% of that.

I don't think I actually need random values as you say, just so that a mix of records are chosen.

I've seen a lot of reference to O(n) but don't actually know what it means? I'll have a look at random permutation.

 

[cotton31]

Thanks ringo747 for answering the questions!

I've tried Any()/Take() as you suggested Dj_Jestar but I'm getting errors about SPListItemCollection not having a reference to those methods.

I've added using System.Linq, so I'm not sure where I've gone wrong.

Thanks,

 

[cotton31]

It's:

'Microsoft.SharePoint.SPListItemCollection' does not contain a definition for 'Any' and no extension method 'Any' accepting a first argument of type 'Microsoft.SharePoint.SPListItemCollection' could be found (are you missing a using directive or an assembly reference?)

 

[cotton31]

OP do yourself a favour and install ReSharper.

You need to reference System.Linq as well as add the using for it.

Next question(s): Why must they be random? Why only 5% needed for this task?

I'll have a look at ReSharper.

How do I reference System.Linq? Not only is this my first Sharepoint app, it's my first C#/.Net app too!! (can you tell? )

Basically the background to this is that I have a list of staff (in Sharepoint) which someone has to survey each month. They have to survey 5% of staff (obviously they don't want to survey the same people each month) and I want to store the results in Sharepoint.

 

[cotton31]

Still getting the same error for using .Any(), .Count() and .OrderBy() as you suggested?

 

[cotton31]

How do you mean?

 

[cotton31]

I didn't mate, not really looked at it since. Swamped with other stuff!

I'm going to try and look at it again this week, so expect more responses in this thread!

 

[cotton31]

Here it is mate, sorry for the delay!

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.SharePoint;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            //Declare sites
            SPSite sourceSite = new SPSite(@"http://sharepoint");

            //Declare webs
            SPWeb sourceWeb = sourceSite.RootWeb;

            //Declare lists
            SPLists sourceList = sourceWeb.GetList("/Lists/Staff Contacts");

            SPListItemCollection sourceItems = sourceList.Items;

            try
            {
                if (sourceList.Items.Any())
                {
                    var numberToTake = 5 / sourceList.Items.Count() * 100;
                    var thePercentOfRecords = sourceList.Items.OrderBy(each => Guid.NewGuid()).Take(numberToTake);
                }

                foreach (int n in thePercentOfRecords)
                {
                    SPListItem item = sourceList.Items[n];
                    String strFirstName = item["First Name"].ToString();
                    String strLastName = item["Last Name"].ToString();
                    String strFullName = strFirstName + " " + strLastName;
                    String strTeam = item["Team"].ToString();

                    CopyItem(strFullName, strTeam);

                }

                sourceWeb.Dispose();
                sourceSite.Dispose();
            }
            catch (Exception e)
            {
                Console.WriteLine(e);
            }
        }

        static void CopyItem(String name, String team)
        {
            //Declare sites
            SPSite destSite = new SPSite(@"http://sharepoint/communications");

            //Declare webs
            SPWeb destWeb = destSite.OpenWeb();

            //Declare lists
            SPList destList = destWeb.Lists["Staff Satisfaction"];

            SPListItemCollection listItems = destList.Items;

            SPListItem item = listItems.Add();

            item["Staff Member"] = name;
            item["Team"] = team;

            item.Update();

            destWeb.Dispose();
            destSite.Dispose();
        }

    }
}