Find all categories with instances

[Anonymous]

Hello, everyone! I'm creating the add-in, some kind of custom filter, and firstly it fills ComboBox with all Categories in the project (code is attached below). 

But, in fact, some categories are empty and haven't any instances in the project, and they're useless in Combobox. 

public void CreateCategoryList()
    {
        FilteredElementCollector elements = new FilteredElementCollector (doc)
        .WhereElementIsElementType();

        categories = elements
        .Where(x => x.Category != null)
        .Select(x => x.Category)
        .Distinct(new CategoryComparer())
        .ToList();

        categories.Sort(new CategoryNameComparer());

        foreach (Category c in categories)
        {

            ComboBoxItem cbi = new ComboBoxItem();
            cbi.HorizontalContentAlignment = HorizontalAlignment.Left;
            cbi.Padding = new Thickness(30, 0, 0, 0);
            cbi.Content = c.Name;
            cbi.Tag = c;
            comboBox.Items.Add(cbi);
        }
    } 

 Can anyone help me to find only those categories which have instances in the project? Thanks!

[Anonymous]

Hello, I do it this way:

var allElelements = new FilteredElementCollector(doc).WhereElementIsNotElementType()
                    .Where(x => (x.Category != null) && x.GetTypeId().IntegerValue != -1).ToList();
            var catsInModel = allElelements.Select(x => x.Category.Name).Distinct().ToList();

[Anonymous]

Thanks, it works better than mine, but still not perfectly. There are 7-8 empty categories in the project. Thank you anyway!

[Anonymous]

Can you give document? I would like to see these empty categories.

[Anonymous]

There might be a more efficient way to do it but this seems to work for me:

List<string> categoriesList = new List<string>();

foreach (Category c in doc.Settings.Categories)
{
    bool foundInstance = false;

    foreach (Element elm in new FilteredElementCollector(doc)
        .WhereElementIsNotElementType()
        .OfCategoryId(c.Id))
    {
        foundInstance = true;
        break;
    }                

    if (foundInstance) categoriesList.Add(c.Name);
}

System.Windows.Forms.MessageBox.Show(
    string.Join(System.Environment.NewLine, categoriesList));