Re: [R] Why aren't row names in a data frame unique?
S+ does allow duplicates in the row names if you ask for them to be allowed (with data.frame(..., dup.row.names=TRUE) or attr(df, "dup.row.names") <- TRUE). They were allowed because bootstrappers were sampling the rows of data.frames with replacement and it turned out that a fair bit of time was being used calling make.unique() on the row names of the sample. There may be better solutions to that problem, but that is why S+ allows them. Bill Dunlap Spotfire, TIBCO Software wdunlap tibco.com > -Original Message- > From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On > Behalf Of Ajay Askoolum > Sent: Monday, March 05, 2012 11:42 PM > To: R General Forum > Subject: [R] Why aren't row names in a data frame unique? > > I expected the row names to be unique but a data frame appears to be able to > hold duplicate row names. > This makes me thing that there must be circumstances when it is necessary. > However, I cannot think of > any. Please enlighten me. > > [[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. __ 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.
Re: [R] Why aren't row names in a data frame unique?
On 06-03-2012, at 11:23, Ajay Askoolum wrote: > Jim, have a look here: > http://www.r-bloggers.com/select-operations-on-r-data-frames/. Specifically > at the Duplicate Row Names section towards the end of the page. > Look carefully at that example. It is NOT providing rownames for a dataframe. It IS providing row names for a matrix. A matrix is not equal to a dataframe. Berend __ 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.
Re: [R] Why aren't row names in a data frame unique?
Jim, have a look here:
http://www.r-bloggers.com/select-operations-on-r-data-frames/. Specifically at
the Duplicate Row Names section towards the end of the page.
From: Jim Lemon
Cc: R General Forum
Sent: Tuesday, 6 March 2012, 9:42
Subject: Re: [R] Why aren't row names in a data frame unique?
On 03/06/2012 06:42 PM, Ajay Askoolum wrote:
> I expected the row names to be unique but a data frame appears to be able to
> hold duplicate row names. This makes me thing that there must be
> circumstances when it is necessary. However, I cannot think of any. Please
> enlighten me.
>
Hi Ajay,
An example of how you managed to do this would be helpful. I tried it:
dodo<-data.frame(a=1:3,b=4:6)
dodo
 a b
1 1 4
2 2 5
3 3 6
rownames(dodo)<-c("s","t","s")
Error in `row.names<-.data.frame`(`*tmp*`, value = value) :
 duplicate 'row.names' are not allowed
In addition: Warning message:
non-unique value when setting 'row.names': âsâ
Jim
[[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.
Re: [R] Why aren't row names in a data frame unique?
On 03/06/2012 06:42 PM, Ajay Askoolum wrote:
I expected the row names to be unique but a data frame appears to be able to
hold duplicate row names. This makes me thing that there must be circumstances
when it is necessary. However, I cannot think of any. Please enlighten me.
Hi Ajay,
An example of how you managed to do this would be helpful. I tried it:
dodo<-data.frame(a=1:3,b=4:6)
dodo
a b
1 1 4
2 2 5
3 3 6
rownames(dodo)<-c("s","t","s")
Error in `row.names<-.data.frame`(`*tmp*`, value = value) :
duplicate 'row.names' are not allowed
In addition: Warning message:
non-unique value when setting 'row.names': ‘s’
Jim
__
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.
[R] Why aren't row names in a data frame unique?
I expected the row names to be unique but a data frame appears to be able to hold duplicate row names. This makes me thing that there must be circumstances when it is necessary. However, I cannot think of any. Please enlighten me. [[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.
