Joins District Factor Group classification to any
district-level dataframe. Handles both full CDS format (county+district,
e.g., "133570") and district-only format (e.g., "3570").
Usage
add_dfg(df, revision = 2000)
Arguments
- df
Dataframe with district_id column
- revision
Numeric. DFG revision year (2000 or 1990). Default 2000.
Value
df with 'dfg' column added