f_park_factors.R

f_park_factors <- function( p_year, p_data, p_hist )
{
  p_data                                                 %>%
  filter( YEAR <= p_year & YEAR >= p_year - p_hist + 1 ) %>%
  group_by( TEAM_ID, PARK_ID )                           %>%
  summarise( H_RS  = sum( x = H_RS )
           , H_RA  = sum( x = H_RA )
           , H_G   = sum( x = H_G  )
           , A_RS  = sum( x = A_RS )
           , A_RA  = sum( x = A_RA )
           , A_G   = sum( x = A_G  )
           , YEARS = n()
           )                                             %>% 
  mutate( YEAR      = p_year
        , PK_FACTOR = ((H_RS + H_RA)/H_G)/((A_RS + A_RA)/A_G) 
        )
}