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  • Bind a SL4 TreeView to an IGrouping using Caliburn

    - by illdev
    I am just starting in the SL world and am trying to use the Caliburn NavigationShell as my starting point. I converted the solution to SL4 and use Caliburn from the trunk . To create the basic navigation, I am a bit unsure (well, quite), how I can display the original StackPanel of Buttons as a collapsible Treeview. I changed ITaskBarItem to own a simple GroupName property public interface ITaskBarItem : IEntryPoint { BitmapImage Icon { get; } string DisplayName { get; } string GroupName { get;} } then, I expose this in ShellViewModel to the View: public IEnumerable<IGrouping<string, ITaskBarItem>> TaskBarItems { get { return _taskBarItems.GroupBy(t => t.GroupName); } } How can I do the xaml markup so that I get a simple hierarchy? How can I bind Actions with out the use of Buttons? GroupName DisplayName DisplayName DisplayName GroupName DisplayName DisplayName DisplayName ... Mind, this is MVVM, so I am not going to use code behind or events to do that...

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  • IGrouping and Casting in Linq

    - by FiveTools
    I have the following query: var groupCats = from g in groups group g by g.Value into grouped select new { GroupCategory = grouped.Key, Categories = GetCategories(grouped.Key, child) }; This works fine. In the anonymous type returned GroupCategory is a string, and Categories are an Enumerable - what is the proper way to declare this instead of using 'var'? I tried: IGrouping<string,string> groupCats = from g in groups group g by g.Value into grouped select new { GroupCategory = grouped.Key, Categories = GetCategories(grouped.Key, child) }; and IGrouping<string,Enumerable<string>> groupCats = from g in groups group g by g.Value into grouped select new { GroupCategory = grouped.Key, Categories = GetCategories(grouped.Key, child) }; In both instances I get: Cannot implicity convert type....An explicit conversion exists (are you missing a cast) How do I cast this?

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  • Should Item Grouping/Filter be in the ViewModel or View layer?

    - by ronag
    I'm in a situation where I have a list of items that need to be displayed depending on their properties. What I'm unsure of is where is the best place to put the filtering/grouping logic of the viewmodel state? Currently I have it in my view using converters, but I'm unsure whether I should have the logic in the viewmodel? e.g. ViewModel Layer: class ItemViewModel { DateTime LastAccessed { get; set; } bool IsActive { get; set; } } class ContainerViewModel { ObservableCollection<Item> Items {get; set;} } View Layer: <TextView Text="Active Items"/> <List ItemsSource={Binding Items, Converter=GroupActiveItemsByDay}/> <TextView Text="Active Items"/> <List ItemsSource={Binding Items, Converter=GroupInActiveItemsByDay}/> or should I build it like this? ViewModel Layer: class ContainerViewModel { ObservableCollection<IGrouping<string, Item>> ActiveItemsByGroup {get; set;} ObservableCollection<IGrouping<string, Item>> InActiveItemsByGroup {get; set;} } View Layer: <TextView Text="Active Items"/> <List ItemsSource={Binding ActiveItemsGroupByDate }/> <TextView Text="Active Items"/> <List ItemsSource={Binding InActiveItemsGroupByDate }/> Or maybe something in between? ViewModel Layer: class ContainerViewModel { ObservableCollection<IGrouping<string, Item>> ActiveItems {get; set;} ObservableCollection<IGrouping<string, Item>> InActiveItems {get; set;} } View Layer: <TextView Text="Active Items"/> <List ItemsSource={Binding ActiveItems, Converter=GroupByDate }/> <TextView Text="Active Items"/> <List ItemsSource={Binding InActiveItems, Converter=GroupByDate }/> I guess my question is what is good practice in terms as to what logic to put into the ViewModel and what logic to put into the Binding in the View, as they seem to overlap a bit?

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  • Looping over ILookup, accessing values

    - by Jono
    I've got a ILookup< string, List<CustomObject> > from some linq I've done. I'd like to now iterate over the results: foreach(IGrouping<string, List<CustomObject>> groupItem in lookupTable) { groupItem.Key; //You can access the key, but not the list of CustomObject } I know I must be misrepresenting a IGrouping as a KeyValuePair, but now I'm not sure how to access it properly.

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  • MapReduce in DryadLINQ and PLINQ

    - by JoshReuben
    MapReduce See http://en.wikipedia.org/wiki/Mapreduce The MapReduce pattern aims to handle large-scale computations across a cluster of servers, often involving massive amounts of data. "The computation takes a set of input key/value pairs, and produces a set of output key/value pairs. The developer expresses the computation as two Func delegates: Map and Reduce. Map - takes a single input pair and produces a set of intermediate key/value pairs. The MapReduce function groups results by key and passes them to the Reduce function. Reduce - accepts an intermediate key I and a set of values for that key. It merges together these values to form a possibly smaller set of values. Typically just zero or one output value is produced per Reduce invocation. The intermediate values are supplied to the user's Reduce function via an iterator." the canonical MapReduce example: counting word frequency in a text file.     MapReduce using DryadLINQ see http://research.microsoft.com/en-us/projects/dryadlinq/ and http://connect.microsoft.com/Dryad DryadLINQ provides a simple and straightforward way to implement MapReduce operations. This The implementation has two primary components: A Pair structure, which serves as a data container. A MapReduce method, which counts word frequency and returns the top five words. The Pair Structure - Pair has two properties: Word is a string that holds a word or key. Count is an int that holds the word count. The structure also overrides ToString to simplify printing the results. The following example shows the Pair implementation. public struct Pair { private string word; private int count; public Pair(string w, int c) { word = w; count = c; } public int Count { get { return count; } } public string Word { get { return word; } } public override string ToString() { return word + ":" + count.ToString(); } } The MapReduce function  that gets the results. the input data could be partitioned and distributed across the cluster. 1. Creates a DryadTable<LineRecord> object, inputTable, to represent the lines of input text. For partitioned data, use GetPartitionedTable<T> instead of GetTable<T> and pass the method a metadata file. 2. Applies the SelectMany operator to inputTable to transform the collection of lines into collection of words. The String.Split method converts the line into a collection of words. SelectMany concatenates the collections created by Split into a single IQueryable<string> collection named words, which represents all the words in the file. 3. Performs the Map part of the operation by applying GroupBy to the words object. The GroupBy operation groups elements with the same key, which is defined by the selector delegate. This creates a higher order collection, whose elements are groups. In this case, the delegate is an identity function, so the key is the word itself and the operation creates a groups collection that consists of groups of identical words. 4. Performs the Reduce part of the operation by applying Select to groups. This operation reduces the groups of words from Step 3 to an IQueryable<Pair> collection named counts that represents the unique words in the file and how many instances there are of each word. Each key value in groups represents a unique word, so Select creates one Pair object for each unique word. IGrouping.Count returns the number of items in the group, so each Pair object's Count member is set to the number of instances of the word. 5. Applies OrderByDescending to counts. This operation sorts the input collection in descending order of frequency and creates an ordered collection named ordered. 6. Applies Take to ordered to create an IQueryable<Pair> collection named top, which contains the 100 most common words in the input file, and their frequency. Test then uses the Pair object's ToString implementation to print the top one hundred words, and their frequency.   public static IQueryable<Pair> MapReduce( string directory, string fileName, int k) { DryadDataContext ddc = new DryadDataContext("file://" + directory); DryadTable<LineRecord> inputTable = ddc.GetTable<LineRecord>(fileName); IQueryable<string> words = inputTable.SelectMany(x => x.line.Split(' ')); IQueryable<IGrouping<string, string>> groups = words.GroupBy(x => x); IQueryable<Pair> counts = groups.Select(x => new Pair(x.Key, x.Count())); IQueryable<Pair> ordered = counts.OrderByDescending(x => x.Count); IQueryable<Pair> top = ordered.Take(k);   return top; }   To Test: IQueryable<Pair> results = MapReduce(@"c:\DryadData\input", "TestFile.txt", 100); foreach (Pair words in results) Debug.Print(words.ToString());   Note: DryadLINQ applications can use a more compact way to represent the query: return inputTable         .SelectMany(x => x.line.Split(' '))         .GroupBy(x => x)         .Select(x => new Pair(x.Key, x.Count()))         .OrderByDescending(x => x.Count)         .Take(k);     MapReduce using PLINQ The pattern is relevant even for a single multi-core machine, however. We can write our own PLINQ MapReduce in a few lines. the Map function takes a single input value and returns a set of mapped values àLINQ's SelectMany operator. These are then grouped according to an intermediate key à LINQ GroupBy operator. The Reduce function takes each intermediate key and a set of values for that key, and produces any number of outputs per key à LINQ SelectMany again. We can put all of this together to implement MapReduce in PLINQ that returns a ParallelQuery<T> public static ParallelQuery<TResult> MapReduce<TSource, TMapped, TKey, TResult>( this ParallelQuery<TSource> source, Func<TSource, IEnumerable<TMapped>> map, Func<TMapped, TKey> keySelector, Func<IGrouping<TKey, TMapped>, IEnumerable<TResult>> reduce) { return source .SelectMany(map) .GroupBy(keySelector) .SelectMany(reduce); } the map function takes in an input document and outputs all of the words in that document. The grouping phase groups all of the identical words together, such that the reduce phase can then count the words in each group and output a word/count pair for each grouping: var files = Directory.EnumerateFiles(dirPath, "*.txt").AsParallel(); var counts = files.MapReduce( path => File.ReadLines(path).SelectMany(line => line.Split(delimiters)), word => word, group => new[] { new KeyValuePair<string, int>(group.Key, group.Count()) });

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  • How to perform group by in LINQ and get a Iqueryable or a Custom Class Object?

    - by VJ
    Here is my query - var data = Goaldata.GroupBy(c => c.GoalId).ToList(); This returns a Igrouping object and I want an Iqueryable object which I can directly query to get the data while in this case I have to loop through using a foreach() and then get the data. Is there another way to group by in LINQ which returns directly a list of Iqueryable or the a List as similar to what happens for order by in LINQ.

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  • linq groupby in strongly typed MVC View

    - by jason
    How do i get an IGrouping result to map to the view? I have this query: var groupedManuals = manuals.GroupBy(c => c.Series); return View(groupedManuals); What is the proper mapping for the ViewPage declaration? Inherits="System.Web.Mvc.ViewPage<IEnumerable<ProductManual>>"

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  • VB.NET GroupBy LINQ statement

    - by Jason
    I am having a bear of a time getting this to work. I have a List(Of MyItem) called Items that have a OrderId property on them. From those items, I want to create a list of Orders. Some items will have the same OrderId so I want to try to group by OrderId. I then want to sort by date. Here's what I have so far: Public ReadOnly Property AllOrders() As List(Of Order) Get Return Items.Select(Function(i As MyItem) New Order(i.OrderID)) _ .GroupBy(Function(o As Order) New Order(o.OrderID)) _ .OrderBy(Function(o As Order) o.DateOrdered).ToList End Get End Property This, of course, doesn't compile, and I get the error: Value of type 'System.Collections.Generic.List(Of System.Linq.IGrouping(Of Order, Order))' cannot be converted to 'System.Collections.Generic.List(Of Order))' I've bolded the part where I think the problem is, but I have no idea how to fix it. Also, it used to work fine (except there were duplicate values) before I added the .GroupBy statement. Anyone have any ideas? Thanks

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  • Easy way to Populate a Dictionary<string,List<string>>

    - by zion
    Greetings Guru's, my objective is to create a Dictionary of Lists, does a simpler technique exist? I prefer the List(t) to IEnumerable(t) which is why I chose the Dictionary of Lists over Ilookup or IGrouping. The code works but it seems like a messy way of doing things. string[] files = Directory.GetFiles (@"C:\test"); Dictionary<string,List<string>> DataX = new Dictionary<string,List<string>>(); foreach (var group in files.GroupBy (file => Path.GetExtension (file))) { DataX.Add (group.Key, group.ToList()); }

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  • Linq Grouping by 2 keys as a one

    - by Evgeny
    Hello! I write a simple OLAP viewer for my web-site. Here are the classes (abstract example): Employee { ID; Name; Roles[]; //What Employee can do } Order { Price; Employee Manager; Employee Executive; //Maybe wrong english. The person which perform order } Employee can be Manager and Executive in the order at the same time. This means that Employee role is not fixed. I have to group orders by employees and finally get IGrouping with Employee key. So .GroupBy(el=new {el.Manager,el.Executive}) is not allowed. I considered some tricks with IEqualityComparable, but found no solution. If somrbody will help I'll be vary glad, thank you.

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  • Groupby in relationtable

    - by Dofs
    I am creating some tag functionality for a forum using linq2sql, and I have two tables [Tag] TagId TagName [ForumTagRelation] TagId ForumId I would like to retrieve, like SO, the most popular tags. I have tried to do this by: List<Tag> popularTags = db.Tags.Select(x => x.ForumTagRelations.GroupBy(y => y.TagId).OrderByDescending(z => z.Count())).Take(count).ToList(); But this just returns the following error: Error 1 Cannot implicitly convert type 'System.Collections.Generic.List<System.Linq.IOrderedEnumerable<System.Linq.IGrouping<System.Guid?,SampleWebsite.ForumTagRelation>>>' to 'System.Collections.Generic.IEnumerable<SampleWebsite.Tag>'. An explicit conversion exists (are you missing a cast?) The question is how I easily can return a list of tags which has the most counts in the ForumTagRelation table?

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