Helping Cynthia with her problem

stringingFormulaVariablesTogether.r

getFormula <- function(checkboxOutput, variablesThatMustAppearInModel) {
  formula <- "testScores ~"
  variables1 <- paste(variablesThatMustAppearInModel, collapse = " + ")
  variables2 <- paste(checkboxOutput, collapse = " + ")
  fullCall <- paste(variables1, 
                    variables2, 
                    collapse = " + ",
                    sep = " + ")
  return(paste(formula, 
               fullCall))  
}

library(ggplot2)

model = do.call(what = lm,
                args = list(formula = getFormula(),
                            data = mpg))

x = c("red", "blue", "green")