Extracts the first two characters from SIC codes to create broader industry classifications.
Details
SIC codes are hierarchical: the first two digits represent major industry groups (e.g., "54" = Retail-Food Stores), while the full 4-digit code provides more specific classifications (e.g., "5412" = Retail-Convenience Stores).
Examples
# Convenience Stores (SIC 5412) -> Retail-Food Stores (54)
sic_2digit(5412)
#> [1] "54"
# [1] "54"
sic_2digit(c(5412, 5400))
#> [1] "54" "54"
# [1] "54" "54"