
Hi Tony,

I "GUESS" my.df[-"DrHorrible"] does not tell R which column "NUMBER" would like to remove.
As we know, we could use my.df[-4] and it exactly tells R which column must remvoer from your data.

 > my.df[-4]
  Angel Buffy Firefly
1     7     8       9
2     8     9       9
3     6     4      10
4     9     9      10
5    10    10      10


I may be not right. 

 

Chunhao

 

 

 

 
> Date: Sun, 22 Feb 2009 14:48:10 -0800
> From: tony.breyal@googlemail.com
> To: r-help@r-project.org
> Subject: [R] Filtering a data frame using a string for colum header
> 
> Hi all,
> 
> I was just radomly playing with R and got the following error when
> trying to filter a data frame using a string:
> 
> > Angel <- c(7,8,6,9,10)
> > Buffy <- c(8,9,4,9,10)
> > Firefly <- c(9,9,10,10,10)
> > DrHorrible <- c(10,9,9,10,10)
> > my.df <- data.frame(Angel, Buffy, Firefly, DrHorrible)
> > my.df["DrHorrible"]
> DrHorrible
> 1 10
> 2 9
> 3 9
> 4 10
> 5 10
> > my.df[-"DrHorrible"]
> Error in -"DrHorrible" : invalid argument to unary operator
> >
> 
> I know how to work around this problem quite easily, I'm just curious
> as to why the my.df[-"DrHorrible] statement didn't work?
> 
> Cheers,
> Tony
> 
> OS = win XP
> > sessionInfo()
> R version 2.8.1 (2008-12-22)
> i386-pc-mingw32
> 
> locale:
> LC_COLLATE=English_United Kingdom.1252;LC_CTYPE=English_United Kingdom.
> 1252;LC_MONETARY=English_United Kingdom.
> 1252;LC_NUMERIC=C;LC_TIME=English_United Kingdom.1252
> 
> attached base packages:
> [1] stats graphics grDevices utils datasets methods
> base
> >
> 
> ______________________________________________
> 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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