Using calculate field to sum values based on two columns, number and string

[MarilynLong1]

Hi,

I'm trying to use calculate field to add values to my column called Trail Length. I want to populate this column by adding together the trail sections that are part of the same trail.

Example:

Trail          Section Length      Trail Length

Trail A          .5                         (script that will add up the values in section length for Trail A, etc)

Trail A          .2

Trail B          5

Trail B           .3

Trail B           1

[DanPatterson]

Summary Statistics (Analysis)—ArcGIS Pro | Documentation does it for you.  See the code sample to call it

[MarilynLong1]

I've used summary stats to do this in the past but how do I incorporate that into the Field Calculator? I've been trying with Python and Arcade but don't know much about scripting and can't get it to work. This is what I have with Arcade:

GroupBy($layer, 'name', { name: 'trail_ft', expression: 'sec_length_ft', statistic: 'SUM'})

'name' is the column with the names of the trails. 'sec_length_ft' is the name of the column with the length of the sections that make up the trail. 'trail_ft' is the name of the column that I want to be updated.