How to best work with codedValues when downloading feature layers from rest servers?

[ar-puuk]

Hi,

First of all, a huge shout out to @elipousson for implementing alias = "label" argument in the arc_read() function.

Along the same vein, let's say I am trying to read the UtahRoads feature layer from an ArcGIS feature server.
https://services1.arcgis.com/99lidPhWCzftIe9K/ArcGIS/rest/services/UtahRoads/FeatureServer/0

In this data, the attribute called "CARTOCODE" (alias: "CartographicCode") has values that are coded as follows: (Details in: https://services1.arcgis.com/99lidPhWCzftIe9K/ArcGIS/rest/services/UtahRoads/FeatureServer/0?f=pjson)

However, when I download the featurelayer using arc_read() I get the code instead of the respective full value.

Now, without manually creating a lookup list, and performing joins, is there a way to easily return the coded values instead of codes? For example: "1 Interstates" instead of "1" or "11 Other Local, Neighborhood, Rural Roads" instead of "11"?

Please advise.

[JosiahParry]

@ar-puuk, please try reinstalled from GitHub and running the following:

library(arcgislayers)

flayer <- arc_open("https://services1.arcgis.com/99lidPhWCzftIe9K/ArcGIS/rest/services/UtahRoads/FeatureServer/0")

res <- arc_select(flayer, n_max = 100)

encode_field_values(res, flayer, field = "CARTOCODE")

@elipousson fixed a small but crucial bug for this functionality.

[JosiahParry]

#235

[ar-puuk]

Awesome, that works great. Thank you both.

PS. Is it too much to ask if this option is available as an argument to arc_read() or the underlying arc_select() function? It could be something like encoded_values:

• If FALSE, returns original
• If TRUE, returns the values as encoded values wherever available
• If a character or a list string is provided, returns encoded values for just those columns.

Not trying to disappoint you, but I am still learning the ways of package development and GitHub contribution, so I do not think I am ready for my own contribution yet.

[ar-puuk]

Also, I believe I have the latest development version, however, when field is NULL I get the following issue:

[JosiahParry]

Could you please create an issue for this? That would be very helpful!

Regarding your suggestion, I think that is not going to be in the cards. The function, as is, is exceptionally complex with 10 possible arguments (more if you're counting what can be passed to ...) a few of which behave differently depending on the type of value provided it. Adding an argument encode that has 4 possible behaviors is definitely making it more complex than it already is.

My philosophy is that each function should be responsible for doing one thing and doing that one thing very well. Each time we add another argument the number of bugs we can have grows exponentially.

I'd much rather a simple pipe than a magic function. I know it may not be the answer you're hoping for, but at the end the day, I've learned that simplicity is better than "automagical". In this case we need to have the FeatureLayer object because it stores the encoding information.

[ar-puuk]

I understand. As long as there is an easy way to fill all encoded values in a feature layer in one function call, that would work great as well. I am hoping that is the case in the encode_field_values() function when the field argument is NULL.