topic Re: Arcade data expression: Calculate the percentage of total based on GroupBy() results in ArcGIS Dashboards Questions

Arcade data expression: Calculate the percentage of total based on GroupBy() results

Merlin — Tue, 21 Dec 2021 11:00:37 GMT

Hi,

today I got stuck writing a data expression that calculates the percentage of several categories based on the frequency of their mentioning in a survey.

To illustrate, I have a survey that allows the user to give multiple topics he would like to know more about in future trainings. These are split by the data expression into seperate rows in order to count them.

This is all fine, in the next step I would like to group and count per given answer. Easy task, just use the GroupBy() function:

return GroupBy(fs_dict, ['split_choices'], [{ name: 'split_count', expression: 'split_choices', statistic: 'COUNT' }]);

Which gives me the following:

Based on this, I can create a nice graph showing these counts, but I cannot tell the percentage of total per question. The total is easly calcuated as variable by counting the filtered result of fv_f. So I would basically like to perform per each row in the above picture an additional calculation to get the percentage.

I tried to use the GroupBy() FS I get in another for-loop but that didn't seem to work, as I am not able to reference the fields correctly, namely split_count.

Any ideas?

All the best,
merlin

Re: Arcade data expression: Calculate the percentage of total based on GroupBy() results

jcarlson — Tue, 21 Dec 2021 14:10:02 GMT

You should keep in mind that if you have a FeatureSet, the chart itself can handle the GroupBy function.

I can have a Data Expression that returns a FeatureSet:

And then let the chart handle the grouping for me by setting it to Grouped Values and choose various statistics.

But to more directly address your issue, you can add another field in your GroupBy to get the percentage, by earlier calculating the total number of responses. Try this:

By using the expression 1 / @ fv_t, your GroupBy function will calculate the per-response percentage, then sum them. For example, each single response out of 2208 responses is worth about 0.000453. If 370 of my responses fall into a given category, then the total percentage of responses that chose that category would be 16.76%.

Re: Arcade data expression: Calculate the percentage of total based on GroupBy() results

Merlin — Mon, 27 Dec 2021 09:14:41 GMT

Excellent, thanky you very much, works like a charm!

I have one minor change/improvement:
I just used 100 / @ fv_t, to get the percentage I want to display right away.

Re: Arcade data expression: Calculate the percentage of total based on GroupBy() results

EdmundEkanem1 — Sat, 11 May 2024 01:24:14 GMT

I am trying to achieve something same result on my end but can't seem to get it right. I am trying to calculate percentage for categories in a field on a single choice question.

I am definately missing something. Please help. see what I did below

var portals = Portal('00');

var fs = FeatureSetByPortalItem(

portals,

'99',

['Formal_level'

false

);

var f_fs = Filter(fs, 'Formal_level IS NOT NULL');

var countf_fs = Count(f_fs);

return GroupBy(f_fs,['Formal_level'],

[{

name: 'name',

expression: '100 / @countf_fs',

statistic: 'SUM'}]);