Subassignment Subsetting http://www.ats.ucla.edu/stat/r/modules/subsetting.htm this section http://adv-r.had.co.nz/Subsetting.html#applications Subsetting http://adv-r.had.co.nz/Subsetting.html Subsetting http://adv-r.had.co.nz/Subsetting.html Subsetting know your subsetting operations well Advanced R Advanced R subsetting section Subsetting Subsetting Subsetting http://www.ats.ucla.edu/stat/r/modules/subsetting.htm http://adv-r.had.co.nz/Subsetting.html