r-input-helpers.R

dtypes <- list(
  "foo"=as.character,
  "bar"=as.integer,
  "letters"=function(x) {
    factor(x, levels=c("a", "b", "c"))
  }
)

ensureAllVariablesExist <- function(df) {
  has.types <- names(dtypes) %in% names(df)
  sum(has.types)==length(dtypes)
}

ensureTypes <- function(df) {
  for(dtype in names(dtypes)) {
    df[,dtype] <- dtypes[[dtype]](df[,dtype])
  }
  df
}

column_order <- c("d", "b", "c", "a")

ensureOrder <- function(df) {
  df[,column_order]
}

model.predict <- function(df) {
  if (! ensureAllVariablesExist(df)) {
    missing.vars <- names(dtypes)[! names(dtypes) %in% names(df)]
    return (list(error="missing variables", "missingVariables"=missing.vars))
  }
  df <- ensureTypes(df)
  df <- ensureOrder(df)
  ...
}