Centrated some variable in the data frame around his mean value.

MeanCenteredFunction.R

centered <- function(centreted_data_frame, var_names){
  centreted_data_frame[var_names] = lapply(var_names, function(name_var){
    centreted_data_frame[name_var]-mean(centreted_data_frame[[name_var]])
  })
  return(centreted_data_frame)
}