filter_results: Filters a data frame by round and equipment class and applies...
In timwilson/soty: Calculate Performance Points For Various Archery Rounds

All event scores are contained in a single data frame. This function filter the data frame by the 'round' and 'class' columns and applies a multiplier to the score column to adjust for a one-day, two-day, or three-day event.

1	filter_results(results, archery_round, equipment_class, multiplier = 1)

`results`	A dataframe containing scores from various archery events.
`archery_round`	The specific round to filter.
`equipment_class`	The specific equipment class to filter.
`multiplier`	A multiplier to apply to each score (default = 1).