# subChick <- ChickWeight[ChickWeight$Time==21 & ChickWeight$Diet %in% c(2,3) ,c("weight","Diet")]
"weight" "Diet"
"232" 331 "2"
"244" 167 "2"
"256" 175 "2"
"268" 74 "2"
"280" 265 "2"
"292" 251 "2"
"304" 192 "2"
"316" 233 "2"
"328" 309 "2"
"340" 150 "2"
"352" 256 "3"
"364" 305 "3"
"376" 147 "3"
"388" 341 "3"
"400" 373 "3"
"412" 220 "3"
"424" 178 "3"
"436" 290 "3"
"448" 272 "3"
"460" 321 "3"