I am using the below code to keep only the most recent
id in a table that has ~4,200 observations with ~4,000 unique id's. The table has ~2,700 columns and some of the id's have multiple timestamps. The script takes 306 seconds to finish.
DT[, .SD[which.max(`timestamp`)], id]
However it only takes fraction of a second when I use
.I to determine the rows that have the most recent timestamp per
DT[, .I[which.max(`die timestamp`)], id]
.SD very slow and what is the best way to retain only the most recent observation by