data.table Subsetting rows by group Selecting groups
Example
# example data
DT = data.table(Titanic)
Suppose we only want to see second class:
DT[ Class == "2nd" ]
# Class Sex Age Survived N
# 1: 2nd Male Child No 0
# 2: 2nd Female Child No 0
# 3: 2nd Male Adult No 154
# 4: 2nd Female Adult No 13
# 5: 2nd Male Child Yes 11
# 6: 2nd Female Child Yes 13
# 7: 2nd Male Adult Yes 14
# 8: 2nd Female Adult Yes 80
Here, we simply subset the data using i, the "where" clause.
