I am seeking guidance on a challenge I am facing with updating the symbology (renderer) of hosted feature layers in ArcGIS Online via the Python API.
In my workflow, I frequently update the underlying data of a hosted feature layer and need the symbology—particularly class breaks and legends—to reflect the new data distribution. While I can update the renderer using the API, I have found that the class breaks and legend often do not recalculate as they do when manually resetting the symbology in the ArcGIS Online web map interface (i.e., by removing and re-adding the field used for styling).
Is there an existing API method or recommended workflow that allows for a full programmatic reset or recalculation of symbology/class breaks, similar to what is possible through the web map UI? If so, I would greatly appreciate any documentation or examples you can provide.
If no such solution currently exists, I would like to request that this capability be considered for future enhancement of the ArcGIS Online API. The ability to programmatically reset and recalculate symbology would significantly improve automated workflows and ensure accurate, up-to-date visualizations for dynamic datasets.
Thank you very much for your assistance. Below, I have included the code that I run in my jupyter notebook in my AGOL account to update the layer. It runs without any error, or warning but there is no update on the values used for style.
from arcgis.mapping import WebMap
from arcgis.features import FeatureLayer
gis= GIS("Home")
webmap_item = gis.content.get("402a4c:The id of the layer")#Not the real ID!
webmap = WebMap(webmap_item)
layer_name = "Temperatures"
layer = None
for lyr in webmap.layers:
if lyr['title'] == layer_name:
layer = lyr
break
if layer is None:
raise ValueError(f"Layer with name '{layer_name}' not found in the WebMap.")
# Correct way to access the URL for FeatureLayer instantiation
feature_layer = FeatureLayer(layer['url'])
temperature_field = "Temp" # Replace with your actual temperature field name
classification_def = {
"type": "classBreaksDef",
"classificationField": temperature_field,
"classificationMethod": "esriClassifyNaturalBreaks", # "esriClassifyEqualInterval", "esriClassifyNaturalBreaks", "esriClassifyQuantile", "esriClassifyStandardDeviation", "esriClassifyManual"
"breakCount": 5 # Adjust as needed
}
renderer_result = feature_layer.generate_renderer(definition=classification_def)
feature_layer.manager.update_definition({"drawingInfo": {"renderer": renderer_result}})
# feature_layer.manager.update_definition({"drawingInfo": renderer_result}) # This method is not very robust and risk losing other symbology settings
webmap.update()
