Modelling team strengths often requires separate parameters for offence and defence. These helper functions provide a quick way to turn a factor of team names into a factor of offence or defence levels

factor_teams(data, columns)



A data frame containing match data.


A charater vector containing the names of columns containing team names.


# For a given dataframe of matches... games <- data.frame( home = c("Arsenal", "Barcelona", "Arsenal"), away = c("Chelsea", "Roma", "Barcelona"), result = c("H", "A", "H"), stringsAsFactors = FALSE ) # Convert the teams to factors games <- factor_teams(games, c("home", "away")) levels(games$home)
#> [1] "Arsenal" "Barcelona" "Chelsea" "Roma"
#> c("Arsenal", "Barcelona", "Chelsea", "Roma")