Hi Roslinazairimah, What you seem to want is fairly simple: dt<-c("AA14068","AA13194","AE11054","AA12251","AA13228", "AA13286","AA14090","AA13256","AA13260","AA13291", "AA14099","AA15071","AA13143","AA14012","AA14039", "AA15018","AA13234","AA13149","AA13282","AA13218") dt[grep(pattern="AA14",dt)] [1] "AA14068" "AA14090" "AA14099" "AA14012" "AA14039"
However, as others have suggested, you may want a more general solution that involves a variable pattern. Jim On Mon, Mar 13, 2017 at 2:32 PM, roslinazairimah zakaria <roslina...@gmail.com> wrote: > Dear r-users, > > I have this list of student ID, > > dt <- c(AA14068, AA13194, AE11054, AA12251, AA13228, AA13286, AA14090, > AA13256, AA13260, AA13291, AA14099, AA15071, AA13143, AA14012, AA14039, > AA15018, AA13234, AA13149, AA13282, AA13218) > > and I would like to extract all student of ID AA14... only. > > I search and tried substrt, subset and select but it fail. > > substr(FKASA$STUDENT_ID, 2, nchar(string1)) > Error in nchar(string1) : 'nchar()' requires a character vector >> subset(FKASA, STUDENT_ID=="AA14" ) > [1] FAC_CODE FACULTY STUDENT_ID NAME PROGRAM KURSUS > CGPA ACT_SS ACT_VAL ACT_CS ACT_LED ACT_PS > ACT_IM > [14] ACT_ENT ACT_CRE ACT_UNI ACT_VOL... > > Thank you so much for your help. > > How do I do it? > -- > *Roslinazairimah Zakaria* > *Tel: +609-5492370; Fax. No.+609-5492766* > > *Email: roslinazairi...@ump.edu.my <roslinazairi...@ump.edu.my>; > roslina...@gmail.com <roslina...@gmail.com>* > Faculty of Industrial Sciences & Technology > University Malaysia Pahang > Lebuhraya Tun Razak, 26300 Gambang, Pahang, Malaysia > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.