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.
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 j...@bitwrit.com.au Cc: R General Forum r-help@r-project.org 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 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?
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.
