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  • What causes a WPF ListCollectionView that uses custom sorting to re-sort its items?

    - by Drew Noakes
    Consider this code (type names genericised for the purposes of example): // Bound to ListBox.ItemsSource _items = new ObservableCollection<Item>(); // ...Items are added here ... // Specify custom IComparer for this collection view _itemsView = CollectionViewSource.GetDefaultView(_items) ((ListCollectionView)_itemsView).CustomSort = new ItemComparer(); When I set CustomSort, the collection is sorted as I expect. However I require the data to re-sort itself at runtime in response to the changing of the properties on Item. The Item class derives from INotifyPropertyChanged and I know that the property fires correctly as my data template updates the values on screen, only the sorting logic is not being called. I have also tried raising INotifyPropertyChanged.PropertyChanged passing an empty string, to see if a generic notification would cause the sorting to be initiated. No bananas. EDIT In response to Kent's suggestion I thought I'd point out that sorting the items using this has the same result, namely that the collection sorts once but does not re-sort as the data changes: _itemsView.SortDescriptions.Add( new SortDescription("PropertyName", ListSortDirection.Ascending));

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  • TabItems from View collection

    - by byte
    I am using MVVM. I have a tab control. I will have a collection of items. I want to display each of this item in the collection as a tab item. The view in each tab item is different and may have its own viewmodel. How do I achieve this? E.g. I have 3 items in the collection. The Tab item template contains an ItemControl. I would like to now have 3 Tabs created and the ItemControls inside each tabitem may be showing different views. One way I could do is have a single view and viewmodel for each item. Now based on some condition the View will display different UI elements and behave differently. But I am afraide this will make the view quite complex over a period of time.

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  • Quickly retrieve the subset of properties used in a huge collection in C#

    - by ccornet
    I have a huge Collection (which I can cast as an enumerable using OfType<()) of objects. Each of these objects has a Category property, which is drawn from a list somewhere else in the application. This Collection can reach sizes of hundreds of items, but it is possible that only, say, 6/30 of the possible Categories are actually used. What is the fastest method to find these 6 Categories? The size of the huge Collection discourages me from just iterating across the entire thing and returning all unique values, so is there a faster method of accomplishing this? Ideally I'd collect the categories into a List.

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  • Java: Set<E> collection, where items are identified by its class

    - by mschayna
    I need Set collection, where its items will be identified by items class. Something like ReferenceIdentityMap from Appache Collections, but on class scope i.e. two different instances of same class must be identified as same in this collection. You know, it is a violation of equals()/hashCode() identity principle but in occasional use it makes sense. I have done this in simple class backing with Map<Class<? extends E>, E>, but due to simplicity it doesn't implement Set<E>. There may be a more elegant solution, decorator of any Set<E> would be great. Is there any implementation of such collection there (Apache/Google/something/... Collections)?

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  • What are the lesser known but cool data structures ?

    - by f3lix
    There a some data structures around that are really cool but are unknown to most programmers. Which are they? Everybody knows linked lists, binary trees, and hashes, but what about Skip lists, Bloom filters for example. I would like to know more data structures that are not so common, but are worth knowing because they rely on great ideas and enrich a programmer's tool box. PS: I am also interested on techniques like Dancing links which make interesting use of the properties of a common data structure. EDIT: Please try to include links to pages describing the data structures in more detail. Also, try to add a couple of words on why a data structures is cool (as Jonas Kölker already pointed out). Also, try to provide one data-structure per answer. This will allow the better data structures to float to the top based on their votes alone.

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  • Is there a standard practice for storing default application data?

    - by Rox Wen
    Our application includes a default set of data. The default data includes coefficients and other factors that are unlikely to ever change but still need to be update-able by the user. Currently, the original default data is stored as a populated class within the application. Data updates are stored to an external XML file. This design allows us to include a "reset" feature to restore the original default data. Our rationale for not storing defaults externally [e.g. XML file] was to minimize the risk of being altered. The overall volume of data doesn't warrant a database. Is there a standard practice for storing "default" application data?

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  • WPF - Listbox bound to collection acts as one item

    - by user553765
    Hi, I have a listbox with the ItemsControl binding the ItemsSource to a readonly collection of strings. The ItemTemplate then declares the DataTemplate as a checkbox where its content is that of the name of the particular item in the collection and IsChecked bound to a property to determine whether or not the item is selected (it's just a listbox of checkboxes) This works fine with one exception - MouseOver the ListBox and it acts as if the collection of Strings is a single item; the whole box acts as if selected. This wouldn't be as much of a problem were it not for this also affecting the scrollbars where they won't get enabled - presumably because it considers the one item as being visible on the screen even though it in actual facts is x+ with only x-y showing on the screen. How do I get the listbox to act as if each individual string is its own item. I assume it acts this way because I declared a datatemplate in order to get a listbox of checkboxes?? Any help would be much appreciated!

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  • Appending an element to a collection using LINQ

    - by SRKX
    I am trying to process some list with a functional approach in C#. The idea is that I have a collection of Tuple<T,double> and I want to change the Item 2 of some element T. The functional way to do so, as data is immutable, is to take the list, filter for all elements where the element is different from the one to change, and the append a new tuple with the new values. My problem is that I do not know how to append the element at the end. I would like to do: public List<Tuple<T,double>> Replace(List<Tuple<T,double>> collection, T term,double value) { return collection.Where(x=>!x.Item1.Equals(term)).Append(Tuple.Create(term,value)); } But there is no Append method. Is there something else?

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  • How can I bind a LinkedList as ItemSource to ListView in WPF XAML?

    - by Jonas
    I'm learning WPF and would like to have a collection similar to a LinkedList, to where I can add and remove strings. And I want to have a ListView that listen to that collection with databinding. How can I do bind a simple list collection to a ListView in XAML? My idea (not working) is something like this: <Window ...> <Window.Resources> <LinkedList x:Key="myList"></LinkedList> <Window.Resources> <Grid> <ListView Height="100" HorizontalAlignment="Left" Margin="88,134,0,0" Name="listView1" VerticalAlignment="Top" Width="120" ItemsSource="{Binding Source={StaticResource myList}}"/> </Grid> </Window>

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  • HQL: illegal attempt to dereference collection

    - by skip
    The situation is like this: I have an entity Book that holds a one-to-many relationship with Chapter. Now if I try the query, "from Book book inner join book.chapters chapter where chapter.title like '%hibernate%'", it gives me the desired result. But if I try, "from Book where book.chapters.title like '%hibernate%'", I get the error illegal attempt to dereference collection. The thing is that I only want the collection of Book objects in return and not a collection of pair of Book and Chapter objects in return which I get with the former query. Could someone help me understand?

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  • java statistics collection for performance evaluation

    - by user384706
    What is the most efficient way to collect and report performance statistic analysis from an application? If I have an application that uses a series of network apis, and I want to report statistics at runtime, e.g. Method doA() was called 3 times and consumed on avg 500ms Method doB() was called 5 times and consumed on avg 1200ms etc Then, I thought of using a well defined data structure (of collection) that each thread updates per remote call, and this can be used for the report. But I think that it will make the performance worse, for the time spend for statistics collection. Am I correct? How would I procceed if I used a background thread for this, and the other threads that did the remote calls were unaware of this collection gathering? Thanks

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  • Why doesn't Java Map extends Collection?

    - by polygenelubricants
    I was surprised by the fact that Map<?,?> is not a Collection<?>. I thought it'd make a LOT of sense if it was declared as such: public interface Map<K,V> extends Collection<Map.Entry<K,V>> After all, a Map<K,V> is a collection of Map.Entry<K,V>, isn't it? So is there a good reason why it's not implemented as such?

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  • Removing an object in a child collection in MongoDB

    - by Jeremy B.
    I've got a collection of content. Said collection has a collection of responses as such Content : [{ 'id' : '1234', 'Responses' : [{ 'id' : '12345' } etc. Now, I want to remove response 12345, but I don't want to remove all of the responses. I can't seem to find the command to do so. I'm getting the impression that the correct action is to grab the object, rebuild the Responses without the one I want removed, and then save the Content object as a whole. Provided there are many responses, this seems like a bad practice to have to load the entire object that way.

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  • Collection type generated by for with yield

    - by Jesper
    When I evaluate a for in Scala, I get an immutable IndexedSeq (a collection with array-like performance characteristics, such as efficient random access): scala> val s = for (i <- 0 to 9) yield math.random + i s: scala.collection.immutable.IndexedSeq[Double] = Vector(0.6127056766832756, 1.7137598183155291, ... Does a for with a yield always return an IndexedSeq, or can it also return some other type of collection class (a LinearSeq, for example)? If it can also return something else, then what determines the return type, and how can I influence it? I'm using Scala 2.8.0.RC3.

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  • Can a variable like 'int' be considered a primitive/fundamental data structure?

    - by Ravi Gupta
    A rough definition of a data structure is that it allows you to store data and apply a set of operations on that data while preserving consistency of data before and after the operation. However some people insist that a primitive variable like 'int' can also be considered as a data structure. I get that part where it allows you to store data but I guess the operation part is missing. Primitive variables don't have operations attached to them. So I feel that unless you have a set of operations defined and attached to it you cannot call it a data structure. 'int' doesn't have any operation attached to it, it can be operated upon with a set of generic operators. Please advise if I got something wrong here.

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  • using key/value collection in session

    - by jumpdart
    Question: What is a good datatype to keep in session for a large collection of keys and values to frequently reference and update? Application: Updating an old .NET web app with a million pages and grids to have all the grids maintain their sort. They currently access helper code to format themselves graphically on load and on sort. I figured I could add to that code to check for a key based on the page and grid id in a collection in session to see if it has a previous expression on load. and the on sort update/add its appropriate item in the collection. Thoughts? Dictionary vs NameValueCollection

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  • ordering a collection by an association's property

    - by neiled
    class Person belongs_to :team class Status #has last_updated property class Team has_many :members, :class => "Person" Ok, so I have a Team class which has many People in it and each of those people has a status and each status has a last_updated property. I'm currently rendering a partial with a collection similar to: =render :partial => "user", :collection => current_user.team.members Now how do I go about sorting the collection by the last_updated property of the Status class? Thanks in advance! p.s. I've just written the ruby code from memory, it's just an example, it's not meant to compile but I hope you get the idea!

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  • is this possible: c# collection of Type with constrains, or collection of generic type?

    - by Jon
    I'm trying to store types in a collection, so that i can later instantiate objects of the types in the collection. But I'm not sure how to do this the best way. What i have so far: List<Type> list = new List<Type>(); list.Add(typeof(MyClass)); var obj = (MyClass)Activator.CreateInstance(list[0]); I would like to have some constrains on the Type, or better yet, just a generic type in the collection instead of an instantiated Type object. Is this possible?

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  • SVN/Trac - OPTIONS reponse did not include requested activity collection set

    - by Jakobud
    We have a trac server on our network, and when I run the following: svn co http://trac.theserver.com/browser/trunk/thefolder . Then I put in my LDAP password, and I get this svn: The OPTIONS response did not include the requested activity-collection-set; this often means that the URL is not WebDAV-enabled What do I need to do to resolve this? The previous IT guy had all sorts of weird ways of setting up stuff on the network.

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  • EMEA Analytics & Data Integration Oracle Partner Forum

    - by milomir.vojvodic
    MONDAY 12TH NOVEMBER, 2012 IN LONDON (UK) For Oracle Partners across Europe, Middle East and Africa: come to hear the latest news from Oracle OpenWorld about Oracle BI & Data Integration, and propel your business growth as an Oracle partner. This event should appeal to BI or Data Integration specialized partners, Executives, Sales, Pre-sales and Solution architects: with a choice of participation in the plenary day and then a set of special interest (technical) sessions. The follow on breakout sessions from the 13th November provide deeper dives and technical training for those of you who wish to stay for more detailed and hands-on workshops. Keynote: Andrew Sutherland, SVP Oracle Technology Hot agenda items will include: The Fusion Middleware Stack: Engineered to work together A complete Analytics and Data Integration Solution Architecture: Big Data and Little Data combined In-Memory Analytics for Extreme Insight Latest Product Development Roadmap for Data Integration and Analytics Venue: Oracles London CITY Moorgate Offices Places are limited, Register from this Link Note: Registration for the conference and the deeper dives and technical training is free of charge to OPN member Partners, but you will be responsible for your own travel and hotel expenses. Event Schedule During this event you can learn about partner success stories, participate in an array of break-out sessions, exchange information with other partners and enjoy a vibrant panel discussion. Nov. 12th  : Day 1 Main Plenary Session : Full day, starting 10.30 am.  Oracle Hosted Dinner in the Evening Nov. 13th  onwards Architecture Masterclass : IM Reference Architecture – Big Data and Little Data combined (1 day) BI-Apps Bootcamp  (4-days) Oracle GoldenGate workshop (1 day) Oracle Data Integrator and Oracle Enterprise Data Quality workshop (1 day) For further information and detail download the Agenda (pdf) or contact Michael Hallett at [email protected] and Milomir Vojvodic at [email protected] v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

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  • Online personal extension collection of Chrome browser

    - by Nam G. VU
    Is it possible to have an online site to see the list/collection of installed extensions of the Chrome browsers installed among my PCs? Please share. ps. I notice that we have the Chrome backup feature which will restore my chrome extensions after we sign in via a Google account. So I need to see the list online somewhere so that to disabled/remove the extensions that I don't wanna waste time reinstalling.

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  • Implementing inotifycollectionchanged interface

    - by George
    Hello, I need to implement a collection with special capabilities. In addition, I want to bind this collection to a ListView, Therefore I ended up with the next code (I omitted some methods to make it shorter here in the forum): public class myCollection<T> : INotifyCollectionChanged { private Collection<T> collection = new Collection<T>(); public event NotifyCollectionChangedEventHandler CollectionChanged; public void Add(T item) { collection.Insert(collection.Count, item); OnCollectionChange(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Add, item)); } protected virtual void OnCollectionChange(NotifyCollectionChangedEventArgs e) { if (CollectionChanged != null) CollectionChanged(this, e); } } I wanted to test it with a simple data class: public class Person { public string GivenName { get; set; } public string SurName { get; set; } } So I created an instance of myCollection class as follows: myCollection<Person> _PersonCollection = new myCollection<Person>(); public myCollection<Person> PersonCollection { get { return _PersonCollection; } } The problem is that the ListView does not update when the collection updates although I implemented the INotifyCollectionChanged interface. I know that my binding is fine (in XAML) because when I use the ObservableCollecion class instead of myCollecion class like this: ObservableCollection<Person> _PersonCollection = new ObservableCollection<Person>(); public ObservableCollection<Person> PersonCollection { get { return _PersonCollection; } } the ListView updates What is the problem?

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