R help - May 2009 - Problem accessing "row number" from subset on a dataframe

I would like to use the "row number" information returned from
performing a subset command on a dataframe.

For example, I would like to automatically delete some rows from a dataframe if
they match a criteria.  Here is my example below.

data(airquality)
names(airquality)
subset(airquality, airquality$Month == 6) 

Now how do I delete the row numbers returned automatically?  

I know I can type
airquality_mod<-airquality[-c(32:60)]

However, I would like to check the row information and then use it to delete the
stuff out of the dataframe.

Thank again for any feedback and insights.

Hi. I may be missing what you're trying to achieve, but...

what about

subset(airquality, airquality$Month!=6)

instead?

You can do arbitrarily complex queries if you wish, combining terms logically.

You don't have to use the subset function. You may find it helpful to
see what the following result in:

airquality$Month==6
airquality[airquality$Month==6, ]
airquality[airquality$Month==6, ]

There are ways of getting the row numbers, but I suspect you don't
actually need to do that, do you?

Best wishes,

Mark

2009/5/26 Jason Rupert <jasonkrupert at
yahoo.com>:
>
>
> I would like to use the "row number" information returned from
performing a subset command on a dataframe.
>
> For example, I would like to automatically delete some rows from a
dataframe if they match a criteria. ?Here is my example below.
>
> data(airquality)
> names(airquality)
> subset(airquality, airquality$Month == 6)
>
> Now how do I delete the row numbers returned automatically?
>
> I know I can type
> airquality_mod<-airquality[-c(32:60)]
>
> However, I would like to check the row information and then use it to
delete the stuff out of the dataframe.
>
> Thank again for any feedback and insights.
>
> ______________________________________________
> R-help at r-project.org mailing list
> 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.
>
>


-- 
Dr. Mark Wardle
Specialist registrar, Neurology
Cardiff, UK

Mark, 

I really apprecaite your response and continue to be amazed by the
responsiveness and support on the R forums.

And, well actually, I would like to get the "row number"(s) and then
delete or not via the row number.

Again, I really appreciate the response...

--- On Tue, 5/26/09, Mark Wardle <mark at wardle.org> wrote:
> From: Mark Wardle <mark at wardle.org>
> Subject: Re: [R] Problem accessing "row number" from subset on a
dataframe
> To: "Jason Rupert" <jasonkrupert at yahoo.com>
> Cc: R-help at r-project.org
> Date: Tuesday, May 26, 2009, 3:18 PM
> Hi. I may be missing what you're
> trying to achieve, but...
> 
> what about
> 
> subset(airquality, airquality$Month!=6)
> 
> instead?
> 
> You can do arbitrarily complex queries if you wish,
> combining terms logically.
> 
> You don't have to use the subset function. You may find it
> helpful to
> see what the following result in:
> 
> airquality$Month==6
> airquality[airquality$Month==6, ]
> airquality[airquality$Month==6, ]
> 
> There are ways of getting the row numbers, but I suspect
> you don't
> actually need to do that, do you?
> 
> Best wishes,
> 
> Mark
> 
> 2009/5/26 Jason Rupert <jasonkrupert at yahoo.com>:
> >
> >
> > I would like to use the "row number" information
> returned from performing a subset command on a dataframe.
> >
> > For example, I would like to automatically delete some
> rows from a dataframe if they match a criteria. ?Here is my
> example below.
> >
> > data(airquality)
> > names(airquality)
> > subset(airquality, airquality$Month == 6)
> >
> > Now how do I delete the row numbers returned
> automatically?
> >
> > I know I can type
> > airquality_mod<-airquality[-c(32:60)]
> >
> > However, I would like to check the row information and
> then use it to delete the stuff out of the dataframe.
> >
> > Thank again for any feedback and insights.
> >
> > ______________________________________________
> > R-help at r-project.org
> mailing list
> > 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.
> >
> >
> 
> 
> 
> -- 
> Dr. Mark Wardle
> Specialist registrar, Neurology
> Cardiff, UK
>