1. Your code is incorrect. All entries are character strings and must be quoted.
2. See ?grep and note in particular (in the "Value" section): "grep(value = TRUE) returns a character vector containing the selected elements of x (after coercion, preserving names but no other attributes)." 3. While the fixed = TRUE option will work here, you may wish to learn about "regular expressions", which can come in very handy for character string manipulation tasks. ?regex in R has a terse, but I have found comprehensible, discussion. There are many good gentler tutorials on the web, also. Cheers, Bert Bert Gunter "The trouble with having an open mind is that people keep coming along and sticking things into it." -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip ) On Sun, Mar 12, 2017 at 8:32 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.
