Convert decimal betting odds to American format

toAmericanOdds.R

# Convert decimal betting odds to American format
#
toAmericanOdds <- function(x) {
  
  if (!is.numeric(x))
    
    x <- as.numeric(x)
    
  # For decimal odds greater than or equal to 2, 
  # American odds = (decimal odds – 1) * 100 
  x[x >= 2.0 & !is.na(x)] <- (x[x >= 2.0 & !is.na(x)] - 1) * 100
  
  # For decimal odds less than 2,
  # American odds = (-100) / (decimal odds - 1)
  x[x < 2.0 & !is.na(x)] <- (-100) / (x[x < 2.0 & !is.na(x)] - 1)
  
  # Remove decimal places
  x <- round(x)
  
  return(x)
 
} # end function

# Sample odds
odds <- c("1.892", "2.000", "1.925", "1.961",
          "1.934", "1.952", NA, "2.020")
          
# Test function
toAmericanOdds(odds)