R/n_offs.R

In engsoccerdata: English and European Soccer Results 1871-2016

#' Return Scorelines that only occurred n times in history
#'
#' note don't try this with 0 - won't return infinite possible scorelines
#' If you pick crazy numbers for the number of times e.g. 34223,
#' you'll get an error message this function is meant for small
#' numbers of occurrences
#'
#' @param df The results dataframe
#' @param N The Number of instances
#' @param Tier Tier
#' @return a dataframe with summary of results.
#' @importFrom magrittr "%>%"
#' @examples
#' n_offs(england, 1) #return results that have occurred only once across all four tiers
#' n_offs(england, 2) #return results that have occurred only twice across all four tiers
#' n_offs(england, 3) #return results that have occurred 3 times across all four tiers
#'
#' n_offs(england, 1, 1) #return which results have occurred only once in the top tier
#' n_offs(england, 1, 4) #return which results have occurred only once in the 4th tier
#' n_offs(england, 2, 2) #return which results have occurred twice in the 2nd tier
#' n_offs(england, 5, 3) #return which results have occurred five times in the 3rd tier
#'
#' @export



n_offs<- function(df=NULL, N=NULL, Tier=NULL){

  n<-.<-Date<-tier<-home<-visitor<-hgoal<-vgoal<-goaldif<-FT<-Season<-division<-result<-maxgoal<-mingoal<-absgoaldif<-NULL


  if(is.null(Tier))
    df %>%
    dplyr::mutate(goaldif  = hgoal-vgoal,
                  result = ifelse(hgoal>vgoal, "H", ifelse(hgoal<vgoal, "A", "D"))) %>%
    dplyr::group_by(FT)%>%
    dplyr::tally() %>%
    dplyr::filter(n==N) %>%
    dplyr::select(FT) %>%
    dplyr::left_join(df) %>%
    dplyr::select(Date, Season, home, visitor, FT, division, tier, result)%>%
    dplyr::arrange(FT, Season)

  else

    { dfTier<-df %>%
      dplyr::mutate(goaldif  = hgoal-vgoal,
                    result = ifelse(hgoal>vgoal, "H", ifelse(hgoal<vgoal, "A", "D"))) %>%
      dplyr::filter(tier==Tier)

    dfTier %>%
      dplyr::group_by(FT)%>%
      dplyr::tally() %>%
      dplyr::filter(n==N) %>%
      dplyr::select(FT) %>%
      dplyr::left_join(dfTier) %>%
      dplyr::select(Date, Season, home, visitor, FT, division, tier, result)%>%
      dplyr::arrange(FT, Season)
    }
}