more on "[<-"
Prof Brian Ripley
Prof Brian Ripley <ripley@stats.ox.ac.uk>
Wed, 18 Nov 1998 16:21:45 +0000 (GMT)
Paul,
you are nowhere using "[<-"! You are using "[" on a vector, and the dim
attribute is not being stripped, only your own "tframe" attribute.
It is clear to me that "[<-" should not change attributes, as it does not:
data <- matrix(rnorm(300),100,3)
attr(data, "tframe") <- c(1981.50, 2006.25 , 4.00)
data[10:90,1] <- rnorm(81)
attributes(data)
on any of these, but it is less clear what [] should do. As it is not
clear if the attributes apply to the whole object only, I suspect stripping
is right.
Brian
> From: Paul Gilbert <pgilbert@bank-banque-canada.ca>
> "[<-" in R 0.63 does not appear to strip attributes, whereas Splus and
previous
> versions of R did.
>
> Paul
> _____
>
> R 0.63:
> > data <- matrix(rnorm(300),100,3)
> > attr(data, "tframe") <- c(1981.50, 2006.25 , 4.00)
> > attributes(data)
> $dim
> [1] 100 3
> $tframe
> [1] 1981.50 2006.25 4.00
> > z <- data[10:90,]
> > attributes(z)
> $dim
> [1] 81 3
> $tframe
> [1] 1981.50 2006.25 4.00
>
> Splus:
> > data <- matrix(rnorm(300),100,3)
> > attr(data, "tframe") <- c(1981.50, 2006.25 , 4.00)
> > attributes(data)
> $dim:
> [1] 100 3
> $tframe:
> [1] 1981.50 2006.25 4.00
> > z <- data[10:90,]
> > attributes(z)
> $dim:
> [1] 81 3
>
--
Brian D. Ripley, ripley@stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272860 (secr)
Oxford OX1 3TG, UK Fax: +44 1865 272595
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