Is there a way using ArcPy to merge features selected from the same layer into a new feature, exactly as the Edit > Merge tool does it? I want to script this, because several dozen merges need to be done on a series of feature selections (iterating through a list of saved SQL expressions). I looked, but could not find.
I am working in ArcGIS Pro 2.0, but I also have ArcGIS Desktop 10.6 available. Thanks for your help.
I'll try to steer you toward creating a new field and populating it by an ID that you can use to either merge together or leave alone, then use Dissolve to make your new feature class. Selections are very slow through Arcpy. An alternative would be to loop through your features using an UpdateCursor and use the Polyline union method to make your new geometries (one feature at a time), but this would be quite a bit more complicated.