Question

raw is a data.table and the following code works:

raw[,r_responseTime] #Returns the whole column
raw[,c_filesetSize]  #Same as above, returns column
plot(raw[,r_responseTime]~raw[,c_filesetSize]) #draws something

Now I want to specify these columns from a string, so for example:

col1="r_reponseTime"
col2="c_filesetSize"

How can I now achieve the same as above while referencing the columns by the string?

raw[,col1] #Returns the whole column
raw[,col2]  #Same as above, returns column
plot(raw[,col1]~raw[,col2]) #draws something

Does not work, of course because I need some kind of “dereferencation”. I didn’t know what to search in the help and the internet, so sorry for the dumb question.

Answer 1

It would be nice if you had provided a reproducible example, or at the very least shown what the column names of raw are and what r_responseTime and c_filesetSize contain. This being said, get is your function for dereferencing so give these a try:

raw[, get(col1)]
raw[, get(col2)]
plot(raw[, get(col1)] ~ raw[, get(col2)])