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In a string list how to split by every 2 character and insert a comma [closed]

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I have a list string which has values like below, could you please let me know how to split the list by every 2 character and insert a comma separated and assign the final list to another list.
var list1 = new List<string>() {"DVMNKL"};
var list2 = new List<string>() {"DV","MN","KL"};
Some time list1 can have only 2 character, at that time I should not split, I have to just assign to list2

You can use System.Linq to manage that.
int splitByCount = 2;
string s = new List<string> { "DVMNLS", "DVMNLS" };
var split = s.SelectMant(c => c) //flatten the list of strings to IEnumerable<char>
.Select((c, index) => new {c, index})
.GroupBy(x => x.index/splitByCount)
.Select(group => group.Select(elem => elem.c))
.Select(chars => new string(chars.ToArray()));
Console.WriteLine(string.Join(",", split));
the output
DV,MN,KL,DV,MN,KL

Get unique items from multiple lists using LINQ- C# [closed]

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I have 3 lists.
ListA<items>
ListB<items>
ListC<items>
I have to select one item from each list but the item.itemID should be unique for each of those items. How can i achieve this? Thanks in advance.

List<items> concat = new List<items>();
concat.AddRange(ListA);
concat.AddRange(ListB);
concat.AddRange(ListC);
List<items> result = new List<items>();
foreach (var item in concat)
{
if (result.Where(x => x.itemId == item.itemId).Count() == 0)
{
result.add(item);
}
}
//result should now contain what you are looking for

So you want exactly one item from each list, where that item hasn't been selected already from a previous list?
Then select from the lists where the ID isn't in the previous selection. Maybe something like this:
var itemA = listA.First(); // any item is unique, since this is our first one
var itemB = listB.First(b => b.ID != itemA.ID);
var itemC = listC.First(c => c.ID != itemA.ID && c.ID != itemB.ID);
If the count of lists isn't known then we'd need to make this a little more dynamic. Maybe something like this:
var selectedItems = new List<Item>();
foreach (var list in listOfLists)
selectedItems.Add(list.First(x => selectedItems.Count(y => y.ID == x.ID) == 0));
What this does is loop through the "list of lists" (since the number of lists isn't known, it must be in a collection data structure) and get the first item from each one where the currently known selected items do not have a matching ID. This should result in one selected item from each list.
(This all assumes that the lists contain a valid item that you're looking for. If that's not the case, you might use FirstOrDefault() instead and check for nulls.)

public class items
{
public int id {get;set;}
}
void Main()
{
var l1=new List<items>{new items {id=1}, new items {id=2}, new items {id=3}};
var l2=new List<items>{new items {id=2}, new items {id=3}, new items {id=4}};
var l3=new List<items>{new items {id=1}, new items {id=2}};
var result=l1
.Join(l2,(k1)=>true,(k2)=>true,(a1,a2)=>new {a1,a2})
.Join(l3,(k1)=>true,(k2)=>true,(b1,b2)=>new {b1.a1,b1.a2,a3=b2})
.Where(rec=>rec.a1.id!=rec.a2.id && rec.a2.id!=rec.a3.id && rec.a1.id!=rec.a3.id)
.First();
Console.WriteLine("{0},{1},{2}",result.a1.id,result.a2.id,result.a3.id);
}
Of the possible answers (132,142,231,241,321,341,342) it will pick and return the first one (132).
Example code: http://csharppad.com/gist/98a076bdd4e01dbd82be

Group by custom list linq c# [closed]

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I have problem in understanding custom group by and order by. Here is the scenario,
I have an object contain data.
Objects->object->name; (structure of the object)
and i want to group by custom list that i have (name is the key object for grouping).
name is like a,b,c and i want b,c,a(sample).
Here is my work around
IOrderedEnumerable<IGrouping<string, Snit>> assetGrouping = sUnits.ToArray().GroupBy(e => e.Name).OrderBy(e => e.Key);
and i want to group and order by my custom list
List<string > customOrder=new List<string>();
customOrder.Add("any");
customOrder.Add("some");
can any body help me..

This is what I scrapped using LINQPad:
Prerequisites:
public class Data
{
public string Name {get; set;}
}
var keys = new[]{"1", "15", "13", "16"};
var random = new Random();
var data = Enumerable.Range(1, 100)
.Select( _ => new Data
{
Name = random.Next(24).ToString()
});
var keys = new[]{"1", "15", "13", "16"};
Now, the grouping:
var grouped = data.GroupBy(x => keys.FirstOrDefault(k=>k==x.Name));
The query above will group the items in data as following: for each value x in data, if there is a key k in keys with k == x.Name, the value will be added to a separate group having the key k; all the other values will be added to a separate group having the key null;
For the ordering of the groups you just need to use the position of each group key in the keys array.
var ordered = grouped.OrderBy( g =>
{
var index = Array.IndexOf(keys, g.Key);
return index == -1 ? int.MaxValue : index;
});
Array.IndexOf will return -1 if the item wasn't found in the dictionary. In this case, according to your needs, the item must be at the end of the collection so return max value. Otherwise, just use the index of the key.
The results are in the image below:

Hash Join Algorithm [closed]

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I have two tables, each one stored in a List.
The table has two columns (thus arrays in lists are of size two)
List<int[]> tablea;
List<int[]> tableb;
Content of tablea
a b
{1,2}
{3,4}
{5,6}
content of tableb
b c
{2,3}
{2,4}
{6,7}
Now I wish to join two tables by field b, hence the result is
a b c
{1,2,3}
{1,2,4}
{5,6,7}
I know I can do this is sort merge join algorithms, and the algorithms is quite intuitive.
But I heard hybrid hashjoin(mentioned here http://en.wikipedia.org/wiki/Hash_join#_note-1) is faster.
May I know how to use hybrid hashjoin algorithms to join tablea and tableb in C#(Preferably) or java?
(What I concern here is speed rather than space)

The ode that can handle non-unique key values, would be like this:
Dictionary<int, List<int[]>> hashA = new Dictionary<int, List<int[]>>();
foreach (int[] a in tablea) {
List<int> list;
if (!hashA.TryGetValue(a[1], out list) {
list = new List<int>();
hashA.Add(a[1], list);
}
list.Add(a);
}
List<int[]> result = new List<int[]>();
foreach (int[] b in tableb) {
List<int[]> a;
if (hashA.TryGetValue(b[0], out a) {
foreach (int[] line in a) {
result.Add(new int[] { line[0], line[1], b[1] });
}
}
}

List<object> compare [closed]

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I have searched for a few examples and not found one that is similar to what I have and what I want to achieve.
I have 2 lists
class object1
{
string obj1_name;
int obj1_qty;
}
List<object1> listA
class object2
{
string obj2_name;
int obj2_qty;
}
List<object2> listB;
Now, using ListA as the primary list I want to see if ListB contains an object with the same name and if so, what is the quantity and hence, does the obj1_qty = obj2_qty each other? if not, there is a difference and I need to show it, most likely in a 3rd list which would be the difference, of the qty's if they exist. Note, ListA can be bigger or smaller than ListB
Show All List A (master list contains all objects)
Show the difference between those names/qty's that exist in both lists.
Gracias

Souncs like a join would work for you:
var query = from a in listA
join b in listB on a.obj1_name equals b.obj2_name
where a.obj1_qty != b.obj2_qty
select new {
Name = a.obj1_name,
QtyA = a.obj1_qty,
QtyB = b.obj2_qty,
Diff = a.obj1_qty - b.obj2_qty
};

The simpelest way to do this is just use a join from Linq
var items = from l1 in listA
join l2tmp1 in listB on l1.obj1_name equals l2.obj2_name into l2tmp2
from l2 in l2tmp2.DefaultIfEmpty();
select new {
ItemA = l1,
ItemB = l2,
Name = l1.obj1_name,
Difference = (l2 == null) ? 0 : l1.ob1_qty - l2.ob2_qty
};
items will now hold a IEnumerable of a anonymous class that holds the a reference to the item in ListA, a reference to the item in listB, the matching name, and the difference.