[R] Extract student ID that match certain criteria

[Ulrik Stervbo]

Hi Roslinazairimah,

As Bert suggested, you should get acquainted with regular expressions. It
can be confusing at times, but pays off in the long run.

In your case, the pattern of "^[A-Z]{2}14.*" might work.

Best,
Ulrik

On Mon, 13 Mar 2017 at 06:20 roslinazairimah zakaria <roslinaump at gmail.com>
wrote:

> Another question,
>
> How do I extract ID based on the third and fourth letter:
>
> I have for example, AA14004, AB15035, CB14024, PA14009, PA14009 etc
>
> I would like to extract ID no. of AB14..., CB14..., PA14...
>
> On Mon, Mar 13, 2017 at 12:37 PM, roslinazairimah zakaria <
> roslinaump at gmail.com> wrote:
>
> > Hi Bert,
> >
> > Thank you so much for your help.  However I don't really sure what is the
> > use of y values.  Can we do without it?
> >
> > x <- as.character(FKASA$STUDENT_ID)
> > y <- c(1,786)
> > My.Data <- data.frame (x,y)
> >
> > My.Data[grep("^AA14", My.Data$x), ]
> >
> > I got the following data:
> >
> >           x   y
> > 1   AA14068   1
> > 7   AA14090   1
> > 11  AA14099   1
> > 14  AA14012 786
> > 15  AA14039   1
> > 22  AA14251 786
> >
> > On Mon, Mar 13, 2017 at 11:51 AM, Bert Gunter <bgunter.4567 at gmail.com>
> > wrote:
> >
> >> 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
> >> <roslinaump at 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 <+60%209-549%202370>; Fax. No.+609-5492766
> <+60%209-549%202766>*
> >> >
> >> > *Email: roslinazairimah at ump.edu.my <roslinazairimah at ump.edu.my>;
> >> > roslinaump at gmail.com <roslinaump at gmail.com>*
> >> > Faculty of Industrial Sciences & Technology
> >> > University Malaysia Pahang
> >> > Lebuhraya Tun Razak, 26300 Gambang, Pahang, Malaysia
> >> >
> >> >         [[alternative HTML version deleted]]
> >> >
> >> > ______________________________________________
> >> > R-help at 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/posti
> >> ng-guide.html
> >> > and provide commented, minimal, self-contained, reproducible code.
> >>
> >
> >
> >
> > --
> > *Roslinazairimah Zakaria*
> > *Tel: +609-5492370 <+60%209-549%202370> <+60%209-549%202370>; Fax. No.
> +609-5492766 <+60%209-549%202766>
> > <+60%209-549%202766>*
> >
> > *Email: roslinazairimah at ump.edu.my <roslinazairimah at ump.edu.my>;
> > roslinaump at gmail.com <roslinaump at gmail.com>*
> > Faculty of Industrial Sciences & Technology
> > University Malaysia Pahang
> > Lebuhraya Tun Razak, 26300 Gambang, Pahang, Malaysia
> >
>
>
>
> --
> *Roslinazairimah Zakaria*
> *Tel: +609-5492370 <+60%209-549%202370>; Fax. No.+609-5492766
> <+60%209-549%202766>*
>
> *Email: roslinazairimah at ump.edu.my <roslinazairimah at ump.edu.my>;
> roslinaump at gmail.com <roslinaump at gmail.com>*
> Faculty of Industrial Sciences & Technology
> University Malaysia Pahang
> Lebuhraya Tun Razak, 26300 Gambang, Pahang, Malaysia
>
>         [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at 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.
>

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