I'm using the code:
setDT(data)[ ,.SD[which.min(Julian_Day)],.(species,year)]
to make a subset of my data set and have to include the library(data.table)
which I made sure to install but I keep getting and error message:
Error in eval(expr, envir, enclos) : could not find function "."
I've used this before in the past with no problem so I'm not sure what's going on.
Thanks in advance!