This function is used within transform_hpop_data() to generate transformed data
on a single column.
Arguments
- df
Data frame in long format, where 1 row corresponds to a specific country, year, and indicator.
- value_col
Column name of column with indicator values.
- transform_col
Column to put transformed values into
- ind_ids
Named vector of indicator codes for input indicators to the Billion. Although separate indicator codes can be used than the standard, they must be supplied as a named vector where the names correspond to the output of
billion_ind_codes().