topic Re: Arcade For Loop & Array in ArcGIS Pro Questions

Arcade For Loop & Array

ChristineSeidel — Tue, 02 Aug 2022 19:43:54 GMT

Hi - I'm using ArcPro 3.0.0 and I'm new to Arcade. Using Calculate Field, I trying to write a bit of Arcade code so it loops thru the values of existing field which has a string of concatenated values (i.e. -99,1,2). Where an item in this string does not equal -99, I want to append the value to a new array and then ultimately return the Mean of the NewArray. So, given -99,1,2 the resulting Mean should = 1.5

So, I've tried the following code but it doesn't work. It just returns Null values:

var NewArray = []
var OrigArray = split($feature.CONCATENATE_Story_Num, ",")
For (var i in OrigArray) {
If (i!=-99) {
NewArray+=OrigArray[i];
}
}
return Mean(NewArray)

Thanks

Re: Arcade For Loop & Array

KenBuja — Tue, 02 Aug 2022 20:02:55 GMT

You can use the Filter function to do this

var arr = [-99,1,2]; function isGood(i) {i != -99} var newarr = Filter(arr, isGood); return Mean(newarr)

Re: Arcade For Loop & Array

jcarlson — Tue, 02 Aug 2022 20:02:57 GMT

There are a few things to address with your expression, but you're most of the way there.

First, you're trying to append to the new array the wrong way. Using += works for numbers and strings, but an array needs to be appended to differently. In the latest versions of Arcade you have access to Push, which will insert an item into an array.

Also, if your original field is a string, you'll need to convert those to numbers.

And lastly, when you're looping over an array, you access the individual array items with array[index], not by calling the index directly, which is just an integer.

Try this:

var NewArray = [] var OrigArray = split($feature.CONCATENATE_Story_Num, ",") for (var i in OrigArray) { If (Number(OrigArray[i]) != -99) { Push(NewArray, OrigArray[i]); } } return Mean(NewArray)

Here's my result running it against '-99,1,2':

Re: Arcade For Loop & Array

jcarlson — Tue, 02 Aug 2022 20:05:25 GMT

Oh, I like this! Sometimes I forget about the array functions. Combining this with Map to get the strings to numbers would be really slick.

Re: Arcade For Loop

ChristineSeidel — Wed, 03 Aug 2022 12:40:22 GMT

Thanks for this solution, Josh. This is exactly what I was looking for. While my original input field is a string of concatenated comma delineated numbers, once it's Split and then recognized as an Array, I didn't have to do any other conversion of string to number.

Thank you!
-Chris

Chris Seidel (pronouns - she, her, hers)
Cartographer/GIS Coordinator
Martha's Vineyard Commission<>
Dukes County Interactive Maps<>
Dukes County GIS Data Hub<>
Mailing: PO Box 1447 Oak Bluffs MA 02557
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Saturdays - working from home; please email: seidel@mvcommission.org

Re: Arcade For Loop

jcarlson — Wed, 03 Aug 2022 13:20:38 GMT

You're welcome! The Arcade Playground and Pro must behave a little differently under the hood, as I couldn't use mathematical functions against the array when I tested it. But I'm glad you got it to work, regardless!

Re: Arcade For Loop & Array

KenBuja — Wed, 03 Aug 2022 14:44:08 GMT

It turns out you don't need a Map function, just a minor modification to the Filter function

var arr = "-99,1,2"; function isGood(i) {i != "-99"} var newarr = Filter(split(arr,","), isGood); return Mean(newarr);

Re: Arcade For Loop & Array

jcarlson — Wed, 03 Aug 2022 14:57:09 GMT

Interesting! Now I'm wondering if I had a typo when I tested it originally. Mean seems to cast array members to numbers automatically.

Re: Arcade For Loop & Array

KenBuja — Wed, 03 Aug 2022 15:10:29 GMT

@jcarlson wrote:
Interesting! Now I'm wondering if I had a typo when I tested it originally. Mean seems to cast array members to numbers automatically.

Yes, which is why your code worked. Otherwise, you would have had to convert the values in OrigArray to a number when you pushed them into NewArray

Re: Arcade For Loop & Array

jcarlson — Wed, 03 Aug 2022 15:27:16 GMT

D'oh!

@ChristineSeidelI think Ken should get the green checkmark here, he has a much more elegant solution than I, and clearly was more careful in how he wrote his expression. I just got lucky!

Re: Arcade For Loop & Array

ChristineSeidel — Wed, 03 Aug 2022 16:35:50 GMT

Thanks Ken. As Josh says, your solution is quite elegant. Being pretty new to Arcade it was easier for me to follow the logic of the For Loop and building a new array ...but it's great to know more ways around the barn. Thank you.

- Chris Seidel

Cartographer - Martha's Vineyard Commission

Re: Arcade For Loop & Array

KenBuja — Wed, 03 Aug 2022 18:18:51 GMT

That's why Josh's replies are always so helpful. He provides a good amount of background information on why things are happening.

Re: Arcade For Loop & Array

JwHayes — Thu, 07 Dec 2023 00:37:51 GMT

Hello Everyone,

I've been trying to apply the great examples in this thread to my circumstance but keep coming up short. I want to convert the text values to number from getData function to the array. I've been trying Push and Number functions but I haven't been able to make it work.

I'm using an address point to query underlying layers, like Plats. There can be multiple Plats overlapping an address point. Ultimately, I want find the most recent Plat and append the Filename to #2 below.

The "Recorded" date field is formatted mm/dd/yyyy.

I included some commented code that I tried. Any help is appreciated. Thanks in advance!!

var getData = FeatureSetByName($datastore, "Plat", ["Filename", "Recorded"]) var PlatDataInt = Intersects(getData, $feature) var platlist = "" //var newarray = [] for (var k in PlatDataInt){ platlist += Right(k.Recorded, 4) + TextFormatting.NewLine //Number(platlist[k]){ //Push(newarray, platlist[k]); //} } return platlist //return Max(platlist) // #1 if (Val == null) return "https://mywebserver/images/survey/NoImage.pdf" // #2 "https://mywebserver/images/survey/Plats/" + Text(Filename)

Re: Arcade For Loop & Array

JwHayes — Fri, 08 Dec 2023 00:24:40 GMT

I was able to get the most recent year from the intersection plats. However, I got so head-down in this I forgot I need to pull the Filename for the most recent plat year.

var getData = FeatureSetByName($datastore, "Plat", ["Filename", "Recorded"]) var platint = Intersects(getData, $feature) var platlist = [] for (var k in platint){ var rdate = k.Recorded var newdate = Right(rdate, 4) var numdate = Number(newdate, '####.') Push(platlist, numdate) } var doc = Max(platlist) return doc