Extract the labels attribute from "labeled" tibble columns from a haven import from Stata

The original question asks how 'to extract the values of the labels attribute to a list.' A solution to the main question follows (assuming some_df is imported via haven and has label attributes):

library(purrr)
n <- ncol(some_df)
labels_list <- map(1:n, function(x) attr(some_df[[x]], "label") )

# if a vector of character strings is preferable
labels_vector <- map_chr(1:n, function(x) attr(some_df[[x]], "label") )

I'm going to take a go at answering this one, though my code isn't very pretty.

First I make a function to extract a named attribute from a single column.

ColAttr <- function(x, attrC, ifIsNull) {
# Returns column attribute named in attrC, if present, else isNullC.
  atr <- attr(x, attrC, exact = TRUE)
  atr <- if (is.null(atr)) {ifIsNull} else {atr}
  atr
}

Then a function to lapply it to all the columns:

AtribLst <- function(df, attrC, isNullC){
# Returns list of values of the col attribute attrC, if present, else isNullC
  lapply(df, ColAttr, attrC=attrC, ifIsNull=isNullC)
}

Finally I run it for each attribute.

stub93 <- AtribLst(cps_00093.df, attrC="label", isNullC=NA)

labels93 <- AtribLst(cps_00093.df, attrC="labels", isNullC=NA)
labels93 <- labels93[!is.na(labels93)]

All the columns have a "label" attribute, but only some are of type "labeled" and so have a "labels" attribute. The labels attribute is named, where the labels match values of the data and the names tell you what those values signify.