topic Re: Best way to omit missing data in client-side feature layer? in ArcGIS JavaScript Maps SDK Questions

Best way to omit missing data in client-side feature layer?

TonyGraham — Tue, 08 Jan 2019 17:40:30 GMT

In the online example "Create a FeatureLayer with client-side graphics", it’s sizing a SimpleMarkerSymbol by the "mag" (magnitude) attribute of the data (earthquakes circa 2016).

For six features in Nevada, the value of "mag" is null. As a result, it looks like the renderer is applying the default size of the SimpleMarkerSymbol (here, set to 20) instead of using the corresponding SizeVariable. So all Nevada’s features missing data are size 20.

My requirement is to omit features with missing data.

In API version 4.6, I was setting the SimpleMarkerSymbol’s default size to 0, which worked. All missing data was size 0.

In API version 4.10, when I set the default size to 0 (l. 185 of the example), no data is drawn for any feature—regardless of the value of "mag".

Is the 4.10 behavior correct? If so, what’s the recommended way to omit missing data? Pre-filter?

Re: Best way to omit missing data in client-side feature layer?

RobertScheitlin__GISP — Tue, 08 Jan 2019 17:58:11 GMT

Tony,

I am not sure if that is how it is suppose to work in 4.10 but one way to handle it is to use this line in the graphic creation portion:

mag: feature.properties.mag || 0,

So if mag is null it will get 0 instead.

Re: Best way to omit missing data in client-side feature layer?

TonyGraham — Tue, 08 Jan 2019 18:13:55 GMT

Thank you. However, if I understood you correctly, changing the feature's null value to zero will still show a (minimum size) marker for it, where I need to omit its marker altogether.

Also, in my own case, any non-null value still needs to be plotted--even zero.

Re: Best way to omit missing data in client-side feature layer?

RobertScheitlin__GISP — Fri, 10 Dec 2021 20:40:20 GMT

Tony,

Oh. In that case make this change then:

        // Create an array of Graphics from each GeoJSON feature
        return geoJson.features.map(function(feature, i) {
          if(feature.properties.mag === null){
            return {};
          }
        ...‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: Best way to omit missing data in client-side feature layer?

ReneRubalcava — Fri, 10 Dec 2021 20:40:22 GMT

The FeatureLayer in 4x is so awesome, that you can do it like you would with a Feature Service, with a definitionExpression.

layer = new FeatureLayer({
  source: graphics, // autocast as an array of esri/Graphic
  // create an instance of esri/layers/support/Field for each field object
  fields: fields, // This is required when creating a layer from Graphics
  objectIdField: "ObjectID", // This must be defined when creating a layer from Graphics
  renderer: quakesRenderer, // set the visualization on the layer
  popupTemplate: pTemplate,
  // Works on client side data too
  definitionExpression: "mag > 0"
  // alternative!!!
  // definitionExpression: "mag IS NOT NULL"
});‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

How cool is that?!

Re: Best way to omit missing data in client-side feature layer?

TonyGraham — Wed, 09 Jan 2019 15:13:47 GMT

Many thanks to you both. Either I'll pre-filter, or I'll set the feature layer's definitionExpression.