Equivalent of “throw” in R

Question

How does one \"throw\" an error in R? I have a function that takes a data frame and some column names and does stuff with them. If the columns don\'t exist, I want the fun

Answer 1

You can check if the column exists and do whatever your want.
Suppose a data.frame named df1 and checking if column col1 exists:

if(! any(grepl('^col1$',colnames(df1)))) stop("nonexistent column")

or

if(! any(grepl('^col1$',colnames(df1)))) return(-1)

For instance