[R] how to use AND in grepl

[Tom Wright]

The first thing I notice here is that your first two subset statements are
searching in an object named Command, not the column df$Command. I'm not at
all sure what you are trying to achieve with the str_extract process but it
is looking for the exact string 'PDT2' the vectors / dataframe formed in
your previous commands are not being used at all.
Moving forward I think you need to pay attention to case "PD" != "pd". Also
the set PDT2 is going to be a subset of both  sets PD and t2, I don't think
this is what you are after.

On Mon, May 2, 2016, 8:49 AM <chalabi.elahe at yahoo.de> wrote:

> Yes it works, but let me explain what I am going to do. I extract all the
> names I want and then create a new column out of them for my plot. This is
> he whole thing I do:
>   PD=subset(df,grepl("pd",Command)) //extract names in Command with only
> "pd"
>   t2=subset(df,grepl("t2",Command)) //extract names with only "t2"
>   PDT2=subset(df,grepl("(.*t2.*pd.*)|(.*pd.*t2.*)",df$Command) // extract
> names which contain both "pd" and "t2"
>   v1=c('PD','t2','PDT2')// I create a vector with these conditions
>   str_extract(df$Command,paste(v1,collaps='|')) //returning patterns,
> using stringr library
>
> here I see no pattern named PDT2 but there are only PD and t2 patterns.
> On Monday, May 2, 2016 8:18 AM, Tom Wright <tom at maladmin.com> wrote:
>
>
>
> 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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