Thanks. Yes, I meant nrow(dataset)+1 (typo...)
Sammy
On Mon, Nov 14, 2011 at 1:29 AM, Petr PIKAL <petr.pi...@precheza.cz> wrote:
> >
> > dataset[ nrow(dataset), ] <- c ("Male", 5, "bad")
> >
> > The above seems to have worked to append a row in place of a rbind().
> This
>
> No. It overwrites your last row. You maybe meant
>
> dataset[ nrow(dataset)+1, ] <- c ("Male", 5, "bad")
>
> Regards
> Petr
>
>
> > method does not drop the custom attributes from the column. Do yo see
> any
> > issue with this method.
> >
> > Thanks,
> > Sammy
> >
> > On Sat, Nov 12, 2011 at 10:16 PM, David Winsemius
> <dwinsem...@comcast.net>wrote:
> >
> > >
> > > On Nov 12, 2011, at 6:40 PM, Sammy Zee wrote:
> > >
> > > Thanks David. Besides rbind(), is there any other way to add a row to
> a
> > >> data frame so that I do not lose the custom attributes.
> > >>
> > >
> > > I have already told you the method that I know of. You don't seem to
> have
> > > taken my poin that it is not a data.frame specific problem but rahter
> a
> > > facor problem. You are welcome to redefine `rbind.data.frame`. The R
> > > language is rather flexible in that manner.
> > >
> > > --
> > > David.
> > >
> > >
> > >> Thanks,
> > >> Sammy
> > >>
> > >> On Sat, Nov 12, 2011 at 5:17 PM, David Winsemius
> <dwinsem...@comcast.net>
> > >> wrote:
> > >>
> > >> On Nov 12, 2011, at 2:47 PM, Sammy Zee wrote:
> > >>
> > >> When I use rbind() or rbind.data.frame() to add a row to an existing
> > >> dataframe, it appears that attributes for the column of type "factor"
> are
> > >> dropped. See the sample example below to reproduce the problem.
> Please
> > >> suggest How I can fix this.
> > >>
> > >>
> > >> Thanks,
> > >> Sammy
> > >>
> > >> a=c("Male", "Male", "Female", "Male")
> > >> b=c(1,2,3,4)
> > >> c=c("great", "bad", "good", "bad")
> > >> dataset<- data.frame (gender = a, count = b, answer = c)
> > >>
> > >> dataset
> > >>
> > >> gender count answer
> > >> 1 Male 1 great
> > >> 2 Male 2 bad
> > >> 3 Female 3 good
> > >> 4 Male 4 bad
> > >>
> > >>
> > >> attributes(dataset$answer)
> > >> $levels
> > >> [1] "bad" "good" "great"
> > >>
> > >> $class
> > >> [1] "factor"
> > >>
> > >> Now adding some custom attributes to column dataset$answer
> > >>
> > >> attributes(dataset$answer)<-c(**attributes(dataset$answer),**
> > >> list(newattr1="custom-attr1"))
> > >> attributes(dataset$answer)<-c(**attributes(dataset$answer),**
> > >> list(newattr2="custom-attr2"))
> > >>
> > >> If you look through the code of rbind.data.frame you see that column
> > >> values are processed with the 'factor' function.
> > >>
> > >>
> > >> > attributes(dataset$answer)
> > >> $levels
> > >> [1] "bad" "good" "great"
> > >>
> > >> $class
> > >> [1] "factor"
> > >>
> > >> $newattr1
> > >> [1] "custom-attr1"
> > >>
> > >> $newattr2
> > >> [1] "custom-attr2"
> > >>
> > >> > attributes(factor(dataset$**answer))
> > >>
> > >> $levels
> > >> [1] "bad" "good" "great"
> > >>
> > >> $class
> > >> [1] "factor"
> > >>
> > >>
> > >> So I think you are out of luck. You will need to restore the "special
> > >> attributes" yourself.
> > >>
> > >> --
> > >> David.
> > >>
> > >>
> > >> attributes(dataset$answer)
> > >> $levels
> > >> [1] "bad" "good" "great"
> > >>
> > >> $class
> > >> [1] "factor"
> > >>
> > >> $newattr1
> > >> [1] "custom-attr1"
> > >>
> > >> $newattr2
> > >> [1] "custom-attr2"
> > >>
> > >> However as soon as I add a row to this data frame ("dataset") by
> rbind(),
> > >> it loses the custom
> > >> attributes ("newattr1" and "newattr2") I have just added
> > >>
> > >> newrow = c(gender="Female", count = 5, answer = "great")
> > >>
> > >> dataset <- rbind(dataset, newrow)
> > >>
> > >> attributes(dataset$answer)
> > >> $levels
> > >> [1] "bad" "good" "great"
> > >>
> > >> $class
> > >> [1] "factor"
> > >>
> > >> the two custom attributes are dropped!! Any suggestion why this is
> > >> happening.
> > >>
> > >> On Fri, Nov 11, 2011 at 11:44 AM, Jeff Newmiller
> > >> <jdnew...@dcn.davis.ca.us>**wrote:
> > >>
> > >> As the doctor says, if it hurts "don't do that".
> > >>
> > >> A factor is a sequence of integers with a corresponding list of
> character
> > >> strings. Factors in two separate vectors can and usually do map the
> same
> > >> integer to different strings, and R cannot tell how you want that
> > >> resolved.
> > >>
> > >> Convert these columns to character before combining them, and only
> convert
> > >> to factor when you have all of your possibilities present (or you
> specify
> > >> them in the creation of the factor vector).
> > >> ------------------------------**------------------------------**
> > >> ---------------
> > >> Jeff Newmiller The ..... ..... Go
> > >> Live...
> > >>
> > >> Sammy Zee <szee2...@gmail.com> wrote:
> > >>
> > >> Hi all,
> > >>
> > >> When I use rbind() or rbind.data.frame() to add a row to an existing
> > >> dataframe, it appears that attributes for the column of type "factor"
> > >> are
> > >> dropped. I see the following post with same problem. However i did
> not
> > >> see
> > >> any reply to the following posting offering a solution. Could someone
> > >> please help.
> > >>
> > >>
> > >> http://r.789695.n4.nabble.com/**rbind-data-frame-drops-**
> > >> attributes-for-factor-**variables-td919575.html<http://r.
> > 789695.n4.nabble.com/rbind-data-frame-drops-attributes-for-factor-
> > variables-td919575.html>
> > >>
> > >> Thanks,
> > >> Sammy
> > >>
> > >> [[alternative HTML version deleted]]
> > >>
> > >> ___
> > >>
> > >>
> > > David Winsemius, MD
> > > West Hartford, CT
> > >
> > >
> >
> > [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-help@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.
>
>
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