Creating Multipart Objects

[JamesCarroll7]

Hi all,

I have a polyline shapefile layer in ArcGIS Pro which shows the road system of a proposed development. All of the roads are on this one layer, but I want to break it down into different selectable sectors for different parts of the development. I used the Multipart to Singlepart tool to break down the shapefile, but I can't find a tool to allow me to select certain polylines to group together (I essentially want to create the equivalent of a block in AutoCAD where all the roads in Sector 1 are grouped together, all the roads in Sector 2 are grouped together etc.). Is it possible to do this in GIS?

[DanPatterson]

not sure if you want the features to remain in the same layer or not.  If you want separate layers for each grouping see

Split By Attributes (Analysis)—ArcGIS Pro | Documentation

or if you want to split by using another geometry layer Split (Analysis)—ArcGIS Pro | Documentation

The opposite of multipart to singlepart is

Dissolve (Data Management)—ArcGIS Pro | Documentation

[DavidSolari]

Like Dan said, Dissolve with the "sector" field should be enough. If you need a more specific workflow, here's an arcpy function that'll condense a bunch of geometries into one multipart:

import ujson
def reduce_geoms(geoms: list[arcpy.Geometry]) -> arcpy.Geometry:
    iter_geom = iter(geoms)
    first = next(iter_geom)
    assert first.type != "point"
    retval = ujson.loads(first.JSON) 
    has_curves = "curvePaths" in retval
    path_key = "curvePaths" if has_curves else "paths"
    for g in iter_geom:
        gson = ujson.loads(g.JSON)
        paths = None
        if "curvePaths" in gson:
            paths = gson["curvePaths"]
            if not has_curves:
                retval["curvePaths"] = retval["paths"]
                del retval["paths"]
                path_key = "curvePaths"
        else:
            paths = retval["paths"]
        retval[path_key].extend(paths)
    return arcpy.AsShape(retval, True)