Track unique character values for variables.

Builds lists of observed unique character values of varlist variables from the data frame.

track_values(dframe, varlist)

Arguments

dframe	Data frame to learn treatments from (training data), must have at least 1 row.
varlist	Names of columns to treat (effective variables).

Value

named list of values seen.

See also

prepare.treatmentplan, novel_value_summary

Examples

set.seed(23525)
zip <- c(NA, paste('z', 1:100, sep = "_"))
N <- 500
d <- data.frame(zip = sample(zip, N, replace=TRUE),
                zip2 = sample(zip, N, replace=TRUE),
                y = runif(N))
dSample <- d[1:300, , drop = FALSE]
tplan <- designTreatmentsN(dSample, 
                           c("zip", "zip2"), "y", 
                           verbose = FALSE)
trackedValues <- track_values(dSample, c("zip", "zip2"))
# don't normally want to catch warnings,
# doing it here as this is an example 
# and must not have unhandled warnings.
tryCatch(
  prepare(tplan, d, trackedValues = trackedValues),
  warning = function(w) { cat(paste(w, collapse = "\n")) })
#> simpleWarning in prepare.treatmentplan(tplan, d, trackedValues = trackedValues): vtreat::prepare: column "zip" has 3 previously unseen values:z_38, z_89, z_71 .