topic Re: Use a data expression to create a new field based on values in another field for use in a pie chart in ArcGIS Dashboards Questions

Use a data expression to create a new field based on values in another field for use in a pie chart

Bec — Mon, 17 Nov 2025 13:32:46 GMT

Hi! I'm trying to build a data expression in an ArcGIS Online dashboard that will take a field called, HOUR_OF_CRASH, which is an integer field and not a time field, and populate a new field called, TOD, which will be a text field for the time of day the hour falls within so that the new field can be used to build a pie chart within the dashboard. The current data expression is shown below.

Unfortunately, this data expression won't function within the dashboard and doesn't give me quite the output I am looking for in the end. See the below image of the output.

My experience with data expression is relatively limited. Any advice would be greatly appreciated!

Bec

Re: Use a data expression to create a new field based on values in another field for use in a pie chart

RPGIS — Mon, 17 Nov 2025 15:37:02 GMT

Hi @Bec,

So the issue is that you are not returning a feature. When creating a custom data expression you should return a value similar to the one below.

Re: Use a data expression to create a new field based on values in another field for use in a pie chart

KenBuja — Mon, 17 Nov 2025 14:38:34 GMT

Also note that you can make the When statement more concise

var tod = When(hour >= 0 && hour <= 5, "Night", hour <= 8, "Morning", hour <= 15, "Day", hour <= 23, "Evening", Null );

Re: Use a data expression to create a new field based on values in another field for use in a pie chart

RPGIS — Mon, 17 Nov 2025 15:45:09 GMT

You could go a more programmatic route.

Re: Use a data expression to create a new field based on values in another field for use in a pie chart

Bec — Mon, 17 Nov 2025 16:09:45 GMT

Yes, RPGIS, your input about returning a FeatureSet was valuable in helping me get to my final output. I made a few more adjustments to the final data expression and what you see below is the working version along with an image of the output.

/// Connect to portal layer var portal = Portal("https://www.arcgis.com"); var fs = FeatureSetByPortalItem( portal, "d651aa4112e5408ea9a1cfabecd6485c", 23 ); // Portal layer is a proxy to REST Service layer called CoC Crash Data // If REST Service layer attributes change may affect data expression // --- Define Output Schema --- var fields = [ { name: "HOUR_OF_CRASH", type: "esriFieldTypeInteger" }, { name: "TOD", type: "esriFieldTypeString" }, { name: "SEVERITY_BY_TYPE_CD", type: "esriFieldTypeString" }, { name: "CRASH_TYPE_CD", type: "esriFieldTypeString" }, { name: "DAY_IN_WEEK_CD", type: "esriFieldTypeString" }, { name: "Month", type: "esriFieldTypeDouble" }, { name: "HIN", type: "esriFieldTypeSmallInteger" }, { name: "ODPS_SPEED_IND", type: "esriFieldTypeString" }, { name: "FUNCTIONAL_CLASS_CD", type: "esriFieldTypeString" }, { name: "ODOT_LANES_NBR", type: "esriFieldTypeDouble" }, { name: "ODOT_YOUNG_DRIVER_IND", type: "esriFieldTypeString" }, { name: "ODPS_SENIOR_DRIVER_IND", type: "esriFieldTypeString" }, { name: "DISTRACTED_DRIVER_IND", type: "esriFieldTypeString" }, { name: "WEATHER_COND_CD", type: "esriFieldTypeString" }, { name: "LIGHT_COND_PRIMARY_CD", type: "esriFieldTypeString" }, { name: "ROAD_COND_PRIMARY_CD", type: "esriFieldTypeString" }, { name: "ODOT_CRASH_LOCATION_CD", type: "esriFieldTypeString" } ]; var features = []; // --- Build Output Records --- for (var f in fs) { var hour = f.HOUR_OF_CRASH; var tod = When( hour >= 0 && hour <= 5, "Night", hour >= 6 && hour <= 8, "Morning", hour >= 9 && hour <= 15, "Day", hour >= 16 && hour <= 23, "Evening", null ); Push(features, { attributes: { HOUR_OF_CRASH: hour, TOD: tod, SEVERITY_BY_TYPE_CD: f.SEVERITY_BY_TYPE_CD, CRASH_TYPE_CD: f.CRASH_TYPE_CD, DAY_IN_WEEK_CD: f.DAY_IN_WEEK_CD, Month: f.Month, HIN: f.HIN, ODPS_SPEED_IND: f.ODPS_SPEED_IND, FUNCTIONAL_CLASS_CD: f.FUNCTIONAL_CLASS_CD, ODOT_LANES_NBR: f.ODOT_LANES_NBR, ODOT_YOUNG_DRIVER_IND: f.ODOT_YOUNG_DRIVER_IND, ODPS_SENIOR_DRIVER_IND: f.ODPS_SENIOR_DRIVER_IND, DISTRACTED_DRIVER_IND: f.DISTRACTED_DRIVER_IND, WEATHER_COND_CD: f.WEATHER_COND_CD, LIGHT_COND_PRIMARY_CD: f.LIGHT_COND_PRIMARY_CD, ROAD_COND_PRIMARY_CD: f.ROAD_COND_PRIMARY_CD, ODOT_CRASH_LOCATION_CD: f.ODOT_CRASH_LOCATION_CD } }); } // --- Return FeatureSet (non-spatial) --- return FeatureSet({ fields: fields, features: features });

Re: Use a data expression to create a new field based on values in another field for use in a pie chart

Bec — Mon, 17 Nov 2025 16:11:55 GMT

Also, very good input from you as well Ken! Thank you for sharing your knowledge and experience.