[R] how to use AND in grepl

[Tom Wright]

Sorry for the missed braces earlier. I was typing on a phone, not the best
place to conjugate regular expressions.
Using the example you provided:

> df=data.frame(Command=c("_localize_PD", "_localize_tre_t2",
"_abdomen_t1_seq", "knee_pd_t1_localize", "pd_local_abdomen_t2"))

> grepl("(.*t2.*pd.*)|(.*pd.*t2.*)",df$Command)
[1] FALSE FALSE FALSE FALSE  TRUE

> subset(df,grepl("(.*t2.*pd.*)|(.*pd.*t2.*)",df$Command))
              Command
5 pd_local_abdomen_t2


On Mon, May 2, 2016 at 7:42 AM, <chalabi.elahe at yahoo.de> wrote:

> Thanks Peter, you were right, the exact grepl is
> grepl("(.*t2.*pd.*)|(.*pd.*t2.*)",df$Command), but it does not change
> anything in Command, when I check the size of it by
> sum(grepl("(.*t2.*pd.*)|(.*pd.*t2.*)",df$Command))  the result is 0, but I
> am sure that the size is not 0. It seems that this AND does not work.
>
>
> On Monday, May 2, 2016 5:05 AM, peter dalgaard <pdalgd at gmail.com> wrote:
>
> On 02 May 2016, at 12:43 , ch.elahe via R-help <r-help at r-project.org>
> wrote:
>
> > Thanks for your reply tom. After using
> Subset(df,grepl("(.*t2.*pd.*)|(.*pd.*t2.*)"),df$Command)  I get this error:
> Argument "x" is missing, with no default. Actually I don't know how to fix
> this. Do you have any idea?
>
> Tom's code was missing a ")" but not where you put one. He probably also
> didn't intend to capitalize "subset".
>
>
> -pd
>
> > Thanks,
> > Elahe
> >
> >
> > On Saturday, April 30, 2016 7:35 PM, Tom Wright <tom at maladmin.com>
> wrote:
> >
> >
> >
> > Actually not sure my previous answer does what you wanted. Using your
> approach:
> > t2pd=subset(df,grepl("t2",df$Command) & grepl("pd",df$Command))
> > Should work.
> > I think the regex pattern you are looking for is:
> > Subset(df,grepl("(.* t2.*pd.* )|(.* pd.* t2.*)",df$Command)
> >
> > On Sat, Apr 30, 2016, 7:07 PM Tom Wright <tom at maladmin.com> wrote:
> >
> > subset(df,grepl("t2|pd",x$Command))
> >>
> >>
> >>
> >>
> >> On Sat, Apr 30, 2016 at 2:38 PM, ch.elahe via R-help <
> r-help at r-project.org> wrote:
> >>
> >> Hi all,
> >>>
> >>> I have one factor variable in my df and I want to extract the names
> from it which contain both "t2" and "pd":
> >>>
> >>> 'data.frame': 36919 obs. of 162 variables
> >>>  $TE                :int 38,41,11,52,48,75,.....
> >>>  $TR                :int 100,210,548,546,.....
> >>>  $Command          :factor W/2229 levels
> "_localize_PD","_localize_tre_t2","_abdomen_t1_seq","knee_pd_t1_localize","pd_local_abdomen_t2"...
> >>>
> >>> I have tried this but I did not get result:
> >>>
> >>> t2pd=subset(df,grepl("t2",Command) & grepl("pd",Command))
> >>>
> >>>
> >>> does anyone know how to apply AND in grepl?
> >>>
> >>> Thanks
> >>> Elahe
> >>>
> >>> ______________________________________________
> >>> 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.
> >>> .
> >
> > ______________________________________________
> > 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.
>
> --
> Peter Dalgaard, Professor,
> Center for Statistics, Copenhagen Business School
> Solbjerg Plads 3, 2000 Frederiksberg, Denmark
> Phone: (+45)38153501
> Office: A 4.23
> Email: pd.mes at cbs.dk  Priv: PDalgd at gmail.com
>

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