Label by attribute

Question

Hi Everbody

I am trying to label a FeatureLayer with values from an attribute, but somehow it fails. I have calculated the z-value and want to label that, but for some reason it label another attribute.

In the CIMLabelClass I define the Expression to be the 'zValue' attribute:

var labelFeatureLayer = new CIMLabelClass
                        {
                            Name = "labelFeatureLayer",
                            ExpressionEngine = LabelExpressionEngine.Arcade,
                            Expression = "$feature.zValue",
                            TextSymbol = SymbolFactory.Instance.ConstructTextSymbol().MakeSymbolReference(),
                            Visibility = true
                        };

var lyrDefn = fcLayer.GetDefinition() as CIMFeatureLayer;
                        var listLabelClasses = lyrDefn.LabelClasses.ToList();
                        listLabelClasses.Add(labelFeatureLayer);
                        lyrDefn.LabelClasses = listLabelClasses.ToArray();
                        fcLayer.SetDefinition(lyrDefn);

fcLayer.SetLabelVisibility(true);

But its just showing a different attribute (in this case its the objectid)

Daniel4 · Answer

Hi, thanks.

I tried with your code @Wolf but ArcGIS Pro doesn't  show the label.

The label tab dont show the new label class:

But if I manual in ArcGis Pro create a label class (eg. 'test'), suddenly the new label class appires:

Do I need to delete some Label Classes before? Or do I need do to something with 'Class 1'?

Wolf · Answer

The following snippet worked for me: protected override async void OnClick() { var fcLayer = MapView.Active.Map.GetLayersAsFlattenedList().OfType().Where(fl => fl.Name == "TestPoints").FirstOrDefault(); await QueuedTask.Run(() => { List newLabels = new List() { new CIMLabelClass { Name = "labelFeatureLayer", ExpressionEngine = LabelExpressionEngine.Arcade, Expression = "Geometry($feature).z", TextSymbol = SymbolFactory.Instance.ConstructTextSymbol().MakeSymbolReference(), Visibility = true } }; var lyrDefn = fcLayer.GetDefinition() as CIMFeatureLayer; lyrDefn.LabelClasses = newLabels.ToArray(); fcLayer.SetDefinition(lyrDefn); fcLayer.SetLabelVisibility(true); }); } @GKmieliauskas is correct as there can be multiple labels with visibility. The snippet above removes all but the new label from the array of labels.

GKmieliauskas · Answer

Hi,

I think you need to switch off visibility for other existing label classes. Look at Esri community sample LabelLineFeatures

//Turn off all the label classes except this one
                foreach (var lc in listLabelClasses)
                {
                    lc.Visibility = lc.Name == "labelFeatureLayer" ? true : false;
                }