extract facies names from stratigraphic column
See also
unique_facies_names()
to get a list of unique facies names
Examples
s = as_stratcol(c(0.5, 1, 0.3, 0.7), c("sand", "shale", "sand", "shale"), L_unit = "m")
facies = facies_names(s)
print(facies)
#> [1] "sand" "shale" "sand" "shale"