topic Re: Arcade Expression - intersecting feature sets with overlapping/split attribute options in ArcGIS Online Questions

Arcade Expression - intersecting feature sets with overlapping/split attribute options

AllisonGoldberg1 — Wed, 11 Dec 2019 21:18:43 GMT

Here is what I have so far:

var intersectLayer =Intersects(FeatureSetByName($map,"PC FPs nonTidal Regulated"), $feature)
var Hazard = "";
for (var f in intersectLayer) {
if (Hazard == "") {
Hazard = f.PC_FHA
} else {
Hazard += " And " + f.PC_FHA;
}
}
return Hazard

What I am looking for next is when there's a parcel that intersects both PC_FHA_NonTidal And PC_FHA_Floodway_NonTidal, I want it to return the option with a higher risk for instance PC_FHA_NonTidal. The parcel referenced is within both areas (hatched and blue symbology) and I want to default to the higher risk flood answer (whatever it ends up being- this is for proof of concept at this stage). The end goal is to have all the risk layer intersections added to the parcel layer for customers to find out information but I am stuck when there are multiple options for a specific parcel boundaries. The popup will end up being very similar to the floodplain inquiry solution but more specific parameters because I want to default to a specific answer when multiple intersecting options are found. Does that make sense? Thank you!

Re: Arcade Expression - intersecting feature sets with overlapping/split attribute options

XanderBakker — Wed, 11 Dec 2019 21:33:01 GMT

Hi Allison Goldberg ,

Thanks for branching your question. It makes sense what you are saying, but in order to determine the highest risk, you will need to use some sort of dictionary of the possible PC_FHA value and the risk level. Do you have such a table?

Re: Arcade Expression - intersecting feature sets with overlapping/split attribute options

AllisonGoldberg1 — Thu, 12 Dec 2019 12:12:17 GMT

Hello Xander Bakker

Thanks for your response. I don't have the dictionary or "key" from the customer yet on the different hazards and zones but if I provide you with a hypothetical one, would that work? For instance, say the possible options for PC_FHA values are A, B, C, D, and E zones. With zone A hypothetically being the lowest risk and zone E as the highest...or a score from 1-5 with A=1 risk (lowest risk), then B=2 (moderate), then C=3 (slightly more moderate), then D=4 (higher risk), and E=5 (highest risk potential). Let's say the parcel shown above is split between Zone B and Zone D, I would then want the expression to only showcase D. Does that help you formulate the language?

Re: Arcade Expression - intersecting feature sets with overlapping/split attribute options

XanderBakker — Sat, 11 Dec 2021 10:51:26 GMT

Hi Allison Goldberg ,

To provide you with an example, see the expression below:

// dictionary with PC_FHA values and the corresponding risk
var risks = {"PC_FHA_NonTidal": 1, 
             "PC_FHA_Floodway_NonTidal": 2,
             "PC_FHA_SomeOtherValue": 3};

// intersect the feature and get the couny
var intersectLayer =Intersects(FeatureSetByName($map,"PC FPs nonTidal Regulated"), $feature);
var cnt = Count(intersectLayer);

// start the analysis
var highest_risk = 0;
var risk_class = "";
var result = "";
if (cnt > 0) {
    for (var f in intersectLayer) {
        var description = f.PC_FHA;
        if (HasKey(risks, description)) {
            // PC_FHA is in risk dictionary
            var risk = risks[description];
            if (risk > highest_risk) {
                // higher risk found
                higest_risk = risk;
                risk_class = description;            
            }
        } else {
            // the PC_FHA is not in the risk dictionary, skip value?
        }
    }
    result = "Flood risk: " + risk_class + "  (" + highest_risk + ")";
} else {
    result = "No risk detected"
}

return result;‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Some explanation:

on lines 2-4 a dictionary is created to provide a risk value for each PC_FHA value (this is an example and you should define your own)
on line 7 the intersect is carried out and line 8 will determine the number of intersecting polygons
on lines 11 - 13 some initial values are defined
on line 14 the analysis is started, but we will only want to do this in case with have intersecting flood polygons (cnt>0)
on line 17 a validation takes place to see if the PC_FHA value is in the risk dictionary (make sure it is)
on line 19 it will get the corresponding risk value based on the PC_FHA value (description)
lines 20 - 23 will see if the risk of the current polygon is higher than the highest value and if so the highest risk and description (class) are updated.
At the end on line 29 the resulting text (highest risk class) will be created and this is returned on line 34

You could potentially extend this to create a multiline output that will indicate the list of risks and their corresponding overlap percentage with the parcel.

Re: Arcade Expression - intersecting feature sets with overlapping/split attribute options

AllisonGoldberg1 — Thu, 12 Dec 2019 14:06:35 GMT

This is really thorough, thanks Xander Bakker. When I tried inputting the new attribute expression (called Highest Risk Test) in the webmap it didn't work (just removed third option to mimic scenario) and the output is blank. I know this is just an example but it should've mimicked it. I have a group created in our AGOL, can I add you to it to take a look at the data in context?

Re: Arcade Expression - intersecting feature sets with overlapping/split attribute options

XanderBakker — Thu, 12 Dec 2019 14:28:44 GMT

Hi Allison Goldberg ,

Sure, that would be better. Things always become a more understandable if one can have a look at the data. You can invite me using my AGOL user "xbakker.spx".

Thanks!

Re: Arcade Expression - intersecting feature sets with overlapping/split attribute options

XanderBakker — Thu, 12 Dec 2019 20:29:28 GMT

Hi agoldberg_Pinellas_eGIS ,

I just had a look at the expression called "Highest Risk Test" and I had a typo at line 19 (see the blue marked text). After correcting the variable name (adding an "h") it seems to work:

Re: Arcade Expression - intersecting feature sets with overlapping/split attribute options

AllisonGoldberg1 — Thu, 12 Dec 2019 20:43:19 GMT

Thanks so much, Xander Bakker. This is exactly what I was looking for in terms of proof of concept. I really appreciate all your assistance. The process makes sense now. Thank you.

Re: Arcade Expression - intersecting feature sets with overlapping/split attribute options

XanderBakker — Thu, 12 Dec 2019 20:54:36 GMT

You're welcome. I'm glad it works!

Re: Arcade Expression - intersecting feature sets with overlapping/split attribute options

XanderBakker — Sat, 11 Dec 2021 10:51:29 GMT

Hi Allison Goldberg

Just to provide you with another example, here is a way you can show more info. I used the FEMA layer as example, but since it has complex multipart polygons, it is pretty slow:

In this case it list the percentage of overlap of the different categories in the parcel. The expression used is:

var FEMA = OrderBy(Intersects($feature, FeatureSetByName($map,"FEMASupportData - Storm Surge 2016")), "CATEGORY DES");
var cnt = Count(FEMA);
var parcelarea = AreaGeodetic($feature, "square-feet");

var result = "FEMA:";
if (cnt > 0) {
    for (var FEMApol in FEMA) {
        var intersectarea = AreaGeodetic(Intersection($feature, FEMApol), "square-feet");
        var category = FEMApol.CATEGORY;
        var percentage = (intersectarea * 100.0) / parcelarea;
        result += TextFormatting.NewLine + " - Category: " + category + "  (" + Round(percentage, 2) + "%)";
    }
} else {
    result = "No risk detected";
}

return result;‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

There is a thing that is not working very well in this demo expression... when you have several polygons of the same FEMA category in one parcel you will have multiple lines. This can be avoided adjusting the expression. If you want to know how, just let me know and I can adjust the example.

Re: Arcade Expression - intersecting feature sets with overlapping/split attribute options

XanderBakker — Sat, 11 Dec 2021 10:51:31 GMT

Hi Allison Goldberg ,

I had a moment to think about how to avoid these redundant lines and this is what should work:

var FEMA = OrderBy(Intersects($feature, FeatureSetByName($map,"FEMASupportData - Storm Surge 2016")), "CATEGORY DES");
var cnt = Count(FEMA);
var parcelarea = AreaGeodetic($feature, "square-feet");

var result = "FEMA:";
var dct = {};
if (cnt > 0) {
    for (var FEMApol in FEMA) {
        var intersectarea = AreaGeodetic(Intersection($feature, FEMApol), "square-feet");
        var category = Text(FEMApol.CATEGORY);
        if (HasKey(dct, category)) {
            dct[category] += intersectarea;
        } else {
            dct[category] = intersectarea;
        }
    }
    for (var category in dct) {
        var percentage = (dct[category] * 100.0) / parcelarea;
        result += TextFormatting.NewLine + " - Category: " + category + "  (" + Round(percentage, 2) + "%)";
    }
} else {
    result = "No risk detected";
}

return result;‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

and a visual result:

Re: Arcade Expression - intersecting feature sets with overlapping/split attribute options

AllisonGoldberg1 — Fri, 13 Dec 2019 12:32:23 GMT

Awesome, thanks so much for everything! This is also really helpful to know how to do as the project progresses. I appreciate all your assistance. Xander Bakker

Re: Arcade Expression - intersecting feature sets with overlapping/split attribute options

XanderBakker — Fri, 13 Dec 2019 14:18:52 GMT

You're welcome agoldberg_Pinellas_eGIS , if you have any follow-up questions just tag me.

Re: Arcade Expression - intersecting feature sets with overlapping/split attribute options

AllisonGoldberg1 — Mon, 30 Dec 2019 17:17:28 GMT

Xander Bakker‌

I was hoping you could maybe help me again for another application. I am working on an attribute expression that involves multipart features. Do I need to convert to single-part to get the desired results? I want to display all future land use options but not duplicate the values. Currently it is showing each multi-part option multiple times. Ideally I would like it (for this example) to be P/ROS/RL. Any idea how to properly format that so the value in the attribute expression occurs only one time? This is what I have so far to display all potential options but want to remove it when it show up multiple times:

var intersectLayer =Intersects(FeatureSetByName($map,"Future Land Use - Unincorporated"), $feature)

var FutureLandUse = "";

for (var f in intersectLayer) {

if (FutureLandUse == "") {

FutureLandUse = f.LANDUSECODE

} else {

FutureLandUse += " / " + f.LANDUSECODE;

}

return FutureLandUse

Any help would be appreciated. Can't seem to find much documentation related to this issue, only ones associated with removing duplicates for labeling. Thank you.

Re: Arcade Expression - intersecting feature sets with overlapping/split attribute options

XanderBakker — Sat, 11 Dec 2021 10:51:34 GMT

Hi agoldberg_Pinellas_eGIS ,

Could you try to include Distinct, like this?

var intersectLayer = Distinct(Intersects(FeatureSetByName($map,"Future Land Use - Unincorporated"), $feature), ["LANDUSECODE"]);

var FutureLandUse = "";
for (var f in intersectLayer) {
    if (FutureLandUse == "") {
        FutureLandUse = f.LANDUSECODE;
    } else {
        FutureLandUse += " / " + f.LANDUSECODE;
    }
}

return FutureLandUse;‍‍‍‍‍‍‍‍‍‍‍‍

This should make the list of land use codes unique.

Re: Arcade Expression - intersecting feature sets with overlapping/split attribute options

AllisonGoldberg1 — Mon, 30 Dec 2019 18:23:30 GMT

That was stupidly easy, didn't know about using "distinct". Thank you! Xander Bakker

Re: Arcade Expression - intersecting feature sets with overlapping/split attribute options

XanderBakker — Mon, 30 Dec 2019 18:36:47 GMT

Hi agoldberg_Pinellas_eGIS ,

I'm glad it worked (I understand it did). To have a look at the entire list of functions, have a look here:

Arcade Function Reference | ArcGIS for Developers

Re: Arcade Expression - intersecting feature sets with overlapping/split attribute options

AllisonGoldberg1 — Tue, 04 Feb 2020 12:22:50 GMT

Hello again Xander,

I was hoping you could assist once again. I am working with the flood customer and she wants a link embedded in the popup when a specific result is obtained. This is what I have so far but the hyperlink isn't showing up in the popup. Do I have to add it as a custom attribute display? I can get the hyperlink to show up properly when the return is just the link but when it's text and the link it just displays as text. This information is in the same web map I originally share with you but under an attribute expression called Test6 if you'd rather take a look at it there. Thank you.

var floodzone = Intersects(FeatureSetByName($map,"FEMASupportData - Storm Surge 2016"), $feature)
If(Count("CATEGORY") > 0) {
return "This property is located in a storm surge area. Get a Plan at <a href=\"https://www.flgetaplan.com\">www.flgetaplan.com</a>. Find out how much flood damage could cost you at <a href=\"https://www.floodsmart.com\">www.floodsmart.com</a>"
} Else {
return 'This property is not located in a storm surge area.'
Xander Bakker‌

Re: Arcade Expression - intersecting feature sets with overlapping/split attribute options

XanderBakker — Wed, 05 Feb 2020 05:40:12 GMT

Hi Allison Goldberg ,

Currently the return type of html is not supported (it is on the road map), so when you construct html it will be interpreted as text. The validation of Count("CATEGORY")>0 will always be true since Count("Category") will return 8 (number of characters). You could apply a Filter to the featureset before you intersect filtering all features where category is larger than 0 and then intersect it, followed by the count.

You will have to use custom html pop-up to be able to achieve this. There is an example explain here showing what you could do: https://community.esri.com/message/905592-re-arcade-text-formatting-bold-text?commentID=905592#comment-905592

Re: Arcade Expression - intersecting feature sets with overlapping/split attribute options

AllisonGoldberg1 — Wed, 05 Feb 2020 12:51:37 GMT

Okay, thanks for the information Xander Bakker