topic Re: ArcGIS Online Notebook how to create buffers and append against existing layer in ArcGIS API for Python Questions

ArcGIS Online Notebook how to create buffers and append against existing layer

ChristopherCounsell — Wed, 25 Sep 2024 01:02:46 GMT

Hi,

I have a Hosted Feature Layer in ArcGIS Online, with a point layer and a polygon layer.

I am looking to run an ArcGIS Notebook as a task that will:

Query the point layer where processed=no
For each point, buffer by a point attribute ("distance_field")
Take the buffer and append to the polygon layer, passing through the distance_field value, a type field and a globalid into parentglobalid. This is required for subsequent processing (and deleting related buffers when the point is updated).

I am having difficulty with the buffer() and use_proximity.create_buffers(). No matter what I do the input geometry seems to be recognized as invalid. Typical error messages are invalid geometry or

an error occured with:list indices must be integers or slices, not str

Here is a basic script:

from arcgis.gis import GIS from arcgis.features import FeatureLayer from arcgis.geometry import buffer from arcgis.features import use_proximity gis = GIS("home") # Get our layers layer_item = gis.content.get("xyzxyzxyz") point_sublayer = layer_item.layers[1] polygon_sublayer = layer_item.layers[2] # Query our point layer # Can set our_sr to 4326 or 3857. WGS84 or projected. points = point_sublayer.query(where="1=1", out_fields="*", return_geometry=True,out_sr = 4326) try: for point in points: p = point.geometry print(type(p)) buffers = buffer(geometries=[p], distances=[5], unit='meters',out_sr=4326) # fails # extra bit would go here to append against polygon except Exception as e: print(f"an error occured with:{str(e)}")

I believe it is because the input is a feature, not a featurecollection or other valid type but I'm not sure how to handle it otherwise.

Re: ArcGIS Online Notebook how to create buffers and append against existing layer

Clubdebambos — Wed, 25 Sep 2024 14:34:02 GMT

Hi @ChristopherCounsell

I got the same error from your code above. See code snippet below for using the geometry.buffer to return the geometry for the buffer polygon. Most notably use the LengthUnits enum and the Point geometry.

Let me know if this works on your end.

from arcgis.geometry import LengthUnits from arcgis.geometry import Point ... for point in points: try: p = Point(point.geometry) buffers = buffer(geometries=[p], distances=[5], unit=LengthUnits.METER.value, in_sr=4326) print(buffers) except Exception as e: print(f"an error occured with: {str(e)}")

You have inspired this blog post.

All the best,

Glen

Re: ArcGIS Online Notebook how to create buffers and append against existing layer

ChristopherCounsell — Sun, 29 Sep 2024 23:20:58 GMT

Thanks @Clubdebambos . The amended geometry / units resolved the issue.

For each point, as we only have one buffer, here's the extra piece to create a polygon feature:

if buffers: new_polygon= { "geometry": buffers[0], "attributes": { "parentglobalid": point.attributes["globalid"] # more attributes here } } # Append the new feature to the polygon layer polygon_layer.edit_features(adds=[new_polygon])