[R] Extract student ID that match certain criteria

[Bert Gunter]

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; Fax. No.+609-5492766*
>
> *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
>
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>
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