Creating a new variable from a lookup table

Question

I have the following columns in my data set:

presult     aresult
  I         single
  I         double
  I         triple
  I         home run
  SS        st         


        

Answer 1

An alternative to Dieter's answer:

dat <- data.frame(
  presult = c(rep("I", 4), "SS", "ZZ"),
  aresult = c("single", "double", "triple", "home run", "strikeout", "home run"),
  stringsAsFactors=FALSE
)

dat$base <- as.integer(factor(dat$aresult,
  levels=c("strikeout","single","double","triple","home run")))-1