Calc Field Tool Question.

[ArmstKP]

When I use the following expression to calculate the Heat Index in AGOL, the expression works great.  When I use this same expression in a calc field tool in Velocity, I get an error.  If I remove the "if" statements, then I don't get an error and can run the analytic.  What am I missing for the reasoning that I am getting this error?

var dictempF = $feature.last_values 
var dicvartempF = Dictionary(dictempF) 
var tempF = Round((dicvartempF.field1.value * 9/5) + 32,1)

var dichumidity = $feature.last_values 
var dicvarhumidity = Dictionary(dichumidity) 
var humidity = Round((dicvarhumidity.field2.value),1)

var T = tempF
var RH = humidity

var HI = -42.379 + 2.04901523*T + 10.14333127*RH - .22475541*T*RH - .00683783*T*T - .05481717*RH*RH + .00122874*T*T*RH + .00085282*T*RH*RH - .00000199*T*T*RH*RH;
if (RH < 13 && T > 80 && T < 112) HI -= ((13-RH)/4)*SQRT((17-ABS(T-95.))/17);
if (RH > 85 && T > 80 && T < 87) HI += ((RH-85)/10) * ((87-T)/5);

if (HI < 80) HI = 0.5 * (T + 61.0 + ((T-68.0)*1.2) + (RH*0.094));

return Round(HI, 1);

Error:

[PeterNasuti]

@ArmstKP Happy to help on this one - but I would need a sample of $feature.last_values to replicate the issue to be provided for the Arcade field sample value. Can you either email it to me (pnasuti@esri.com), Esri Community private message a sample, or post here if it is data that can be seen by the public? Thanks!

[ArmstKP]

@PeterNasuti here is a sample of $feature.last_values:

{"field4":{"value":5,"created_at":"2023-09-26T20:17:05Z"},"log":{"value":507,"created_at":"2023-09-26T13:38:07Z"},"field3":{"value":157.88,"created_at":"2023-09-26T20:17:06Z"},"field1":{"value":22.0706,"created_at":"2023-09-26T20:17:05Z"},"field2":{"value":54.8348,"created_at":"2023-09-26T20:17:05Z"},"field5":{"value":-47,"created_at":"2023-09-26T20:12:09Z"},"wifi":{"value":"fe:55:a8:0a:40:ef,-55;ee:55:a8:0a:40:ef,-56;02:6a:e3:84:cf:05,-79;94:57:a5:79:5d:7d,-84;88:5a:85:f5:f9:9f,-85","created_at":"2023-09-26T13:42:54Z"}}

[JeffSilberberg]

A couple of questions although Peter will probably have a better answer --  

Your if ( ) {TRUE};  Startments are missing the brackets...

You appear to be using the same data for Temperature and Humidity?

$feature.last_values

https://developers.arcgis.com/arcade/guide/logic/

Also, why are the there three IF statements versus an if - else? 

[PeterNasuti · Accepted solution]

@ArmstKP I have traced down the cause of this to a few things

1. The "95." on line 13 should be 95 or 95.0
2. Taking a square root of a negative number generating an imaginary number on line 13 is also causing failure. To address this I wrapped the calculation in another ABS() function before the SQRT() function
3. I changed the logic pattern to IIf() functions that update the "HI" variable and also handle the false case. I often recommend this IIf() function in Arcade configurations of Velocity

var dictempF = $feature.last_values 
var dicvartempF = Dictionary(dictempF) 
var tempF = Round((dicvartempF.field1.value * 9/5) + 32,1)

var dichumidity = $feature.last_values 
var dicvarhumidity = Dictionary(dichumidity) 
var humidity = Round((dicvarhumidity.field2.value),1)

var T = tempF
var RH = humidity
var HI = -42.379 + 2.04901523*T + 10.14333127*RH - .22475541*T*RH - .00683783*T*T - .05481717*RH*RH + .00122874*T*T*RH + .00085282*T*RH*RH - .00000199*T*T*RH*RH;

HI = IIf((RH < 13 && T > 80 && T < 112), HI - (((13-RH)/4)*SQRT(ABS((17-ABS(T-95))/17))), HI);
HI = IIf((RH > 85 && T > 80 && T < 87), HI + (((RH-85)/10) * ((87-T)/5)), HI);
HI = IIf((HI < 80), (0.5 * (T + 61.0 + ((T-68.0)*1.2) + (RH*0.094))), HI);

return Round(HI, 1);

Let me know if this addresses the validation error on your side as well and if there is anything else that comes up.

Thanks,

Peter Nasuti

[ArmstKP]

@PeterNasuti Thank you for the help and reasoning.  This cleared the error, enabling me to run the analytic.

Appreciate it!!!