Set line colour based off of attribute values using arcade in ArcGIS Online

Keiran_Bray

Evening all,

I'm currently working on a project where I need to symbolize a footpath polyline based off of two values,

The first value is used to set the symbol type using unique values i.e. paved, sealed, concrete etc

The second value is used to set the colour based off of footpath condition values ranging from 0-5 with specific breaks according to certain condition values i.e 0-0.99, 1-1.99....,

So far I have been able to achieve this within ArcGIS Pro using attribute driven symbology based off of this post: https://community.esri.com/t5/commercial-blog/color-me-impressed-with-attribute-driven-symbology/ba-p/884355

Which was great however this does not come across to ArcGIS Online when publishing this as a feature layer, I have found a few posts referencing how to do this with text in a pop-up using something similar to below:

var cd = $feature.condition

if (cd >= 0 && cd <= 0.99){return "#38A800"}
if (cd >= 1 && cd <= 1.99){return "#7ACB00"}
if (cd >= 2 && cd <= 2.99){return "#CEEE00"}
if (cd >= 3 && cd <= 3.99){return "#FFFF73"}
if (cd >= 4 && cd <= 4.99){return "#FF6600"}
if (cd == 5){return "#FF0000"}

but this does not seem to work when I try to set this within ArcGIS Online or ArcGIS Pro when using "Vary Symbology by attribute" and setting the expression to change the symbol colour :

I've also tried using the when() function but could not get that to work either

Is it possible to set symbol type and using arcade to set polyline colour based off of specific integer values?

jcarlson

It's sort of possible, but it's going to be tedious.

The "vary color by attribute" setting in Pro only really works for numeric values, and it will scale the color based on number and a color ramp. These values don't translate well to a legend, either. And as you've found, these don't carry over to AGOL.

What you're really trying to do is create unique symbols based on two fields. AGOL won't let you do this and treat things as categories; you can only use multiple fields with numeric values, not two categorical fields.

The best you can do is base the symbology on an expression:

var cd = $feature.condition

var cd_cat = When(
    cd >= 0 && cd <= 0.99, 'good',
    cd >= 1 && cd <= 1.99, 'fair',
    cd >= 2 && cd <= 2.99, 'adequate',
    cd >= 3 && cd <= 3.99, 'poor',
    cd >= 4 && cd <= 4.99, 'bad',
    cd == 5, 'just the worst',
    'no value'
)

return `${$feature.surface} - ${cd_cat}`

 

But you'll run into a couple issues. First, if you have 5 surface types and 6 conditions, there are potentially 30 unique symbols you'll need to configure. Like I said, tedious.

Second, in AGOL, you only get to configure symbols for values that are present in the data. So of the 30 potential combinations, if only half are present when the symbology is configured, then you won't be able to set the symbology for the remaining combinations. If one of those appear later, it will not be symbolized correctly, and you'll need to open the layer to adjust the symbology to catch that new type.

There's a workaround for the second point, that you can set the symbology for non-present values in ArcGIS Pro and save the web map from there, but it's still going to be tedious.

On the other hand, if you don't classify that other field, AGOL can get you colors from one field and width from the numeric field, but this might not be what you want for your map.