ansaurus

Question

Answer 1

+1 A:

Can you add to all of your objects a variable "BeenThereInHere" (or whatever name you want) that would be set to true if one of his children has userHaveBeenThere==true, that way, you can quickly nail down where to scan and where you can skip it to save time.

Wildhorn 2010-08-10 17:26:51

it sounds interesting. I think I could :)

2010-08-10 17:28:42

So, what's your idea ?

2010-08-10 17:40:53

Then you keep in memory the path of the tree you went throu to reach the last node. Create a temporary treeview of it and keep going throu the scan to fill the temp treeview. Then you will have your filtered list.

Wildhorn 2010-08-10 20:41:18

Answer 2

+1 A:

Is the data in a database or stored as a graph?

If it's a database, you could set up queries to get the right data.

If it's a graph, you could made it bidirectional, start at the bottom ( visited hotels ) and walk to each root ( regions ) inserting the parents into a new object.

sfossen 2010-08-10 18:29:20

Answer 3

+1 A:

I would suggest using recursion. For node that can be Country, Province, City, Hotel do as follow:

bool ShouldDisplayNode(Node n){
    if (n.Type == Hotel){
        return n.HasBeenThere;
    }
    bool display = false;
    foreach (var child in n.Children){
        display |= ShouldDisplayNode(child);
    } 
    return display;
}

I don't know exact data structure but above method would be very useful when you will use Composite Pattern to represent this hierarchical structure. You will also need to have some kind of dictionary or property in item to store calculated flags.

jethro 2010-08-10 18:44:03

Answer 4

A:

This is my solution:

 var copiedCountry = CloneObject(_package.Country);


            for (int indexOfRegion = 0; indexOfRegion < copiedCountry.ListOfRegions.Count; indexOfRegion++)
            {
                var region = copiedCountry.ListOfRegions[indexOfRegion];
                if (region.ListOfProvinces.Count > 0)
                {
                    for (int indexOfProvince = 0; indexOfProvince < region.ListOfProvinces.Count; indexOfProvince++)
                    {
                        var province = region.ListOfProvinces[indexOfProvince];
                        if (province.ListOfCities.Count > 0)
                        {
                            for (int indexOfCity = 0; indexOfCity < province.ListOfCities.Count; indexOfCity++)
                            {
                                var city = province.ListOfCities[indexOfCity];
                                int numberOfHotels = city.ListOfHotels.Count;
                                for (int indexOfHotel = 0; indexOfHotel < numberOfHotels; indexOfHotel++)
                                {
                                    var hotel = city.ListOfHotels[indexOfHotel];
                                    if (hotel.userHaveBeenThere  == false)
                                    {
                                        city.ListOfHotels[indexOfHotel] = null;
                                    }
                                }

                                city.ListOfHotels.RemoveAll(h => h == null);

                                if (city.ListOfHotels.Where(h => h.userHaveBeenThere  == true).Count() > 0)
                                {

                                }
                                else
                                {
                                    if (city.userHaveBeenThere  == false)
                                    {
                                        province.ListOfCities[indexOfCity]=null;
                                    }

                                }
                            }

                            province.ListOfCities.RemoveAll(c => c == null);

                            if (province.ListOfCities.Count == 0)
                            {
                                if (province.userHaveBeenThere  == false)
                                {
                                    region.ListOfProvinces[indexOfProvince]=null;
                                }
                            }



                        }
                        else
                        {
                            if (province.userHaveBeenThere  == false)
                            {
                                region.ListOfProvinces[indexOfProvince] = null;
                            }
                        }
                    }

                    region.ListOfProvinces.RemoveAll(p => p == null);

                    if (region.ListOfProvinces.Count == 0)
                    {
                        if (region.userHaveBeenThere  == false)
                        {
                            copiedCountry.ListOfRegions[indexOfRegion]=null;
                        }
                    }
                }
                else
                {
                    if (region.userHaveBeenThere  == false)
                    {
                        copiedCountry.ListOfRegions[indexOfRegion]=null;
                    }
                }

                copiedCountry.ListOfRegions.RemoveAll(r => r == null);
            }


public static T CloneObject<T>(T item)
        {
            using (MemoryStream ms = new MemoryStream())
            {

                BinaryFormatter bf = new BinaryFormatter(null,
                          new StreamingContext(StreamingContextStates.Clone));

                try
                {
                    bf.Serialize(ms, item);
                }
                catch (Exception e)
                {
                    throw;
                }


                ms.Seek(0, SeekOrigin.Begin);


                return (T)bf.Deserialize(ms);
            }
        }

I think that there is a lot to optimize :/

2010-08-11 10:13:16

Answer 5

+1 A:

Instead of using a bool to know if the user has been there, consider using a bool?. Set it to null when you want to redirect to the child object's userHasBeenThere.

Here is a concrete example, the magic happens when you will set one of thoses object's userHasBeenThere to true.

Here is an example of the pattern:

public abstract class AUserTracker
{
    private IEnumerable<AUserTracker> _children;
    public IEnumerable<AUserTracker> Children
    {
        get { return _children; }
        set { _children = value; }
    }

    private bool? _userHasBeenThere;
    public bool UserHasBeenThere
    {
        get
        {
            if (_userHasBeenThere == null)
            {
                _userHasBeenThere = false;
                // Uses OR operator, any child will trigger the show up.
                foreach (AUserTracker child in Children)
                    _userHasBeenThere |= child.UserHasBeenThere;
            }
            return _userHasBeenThere ?? false;
        }
    }
}

This would be the base class for all your objects. Then you can use WPF HierarchicalDatatemplate to show up your objects in the TreeView.

{enjoy}

Micael Bergeron 2010-08-12 21:40:40

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Algorithm for filtering collection

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