[R] Inherit names ...

[Thomas Lumley]

On Wed, 20 Jan 1999, John Logsdon wrote:

> No doubt an easy answer to this exists.
> 
> I have a data frame which comprises 4 matrices and 2 vectors:
> 
> year(1024,6),growth(1024,6),ycens(1024,6),gcens(1024,6),yinit(1024),ginit(1024)
> 
> The names of the 26 columns get denoted as y.1 to y.6, g.1 to g.6, yc.1 to
> yc.6, gc.1 to gc.6, yi and gi as these are the internal names.
> 
> I wish to make a subset of the data using the logical vector R1(length
> 1024) so that only the cases where R1 is TRUE are included.  I can do this
> by:
> 
> R1data<-alldata[R1]

R1data<-alldata[R1,] is what you want (note the comma)

 
> (c) Is there a way within a data frame to refer conveniently to a group of
> columns (ie one of the constituent matrices in the case above)? 
> 

	alldata[,c(1,3,5,11:20)]
would give the first, third, fifth, and eleventh through twentieth
columns, or you can refer to them by name: eg
	alldata[,c("y.2","gc.4","gi")]



Thomas Lumley
Assistant Professor, Biostatistics
University of Washington, Seattle

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