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  The functions \code{.subset} and \code{.subset2} are essentially
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  The functions \code{.subset} and \code{.subset2} are essentially
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  equivalent to the \code{[} and \code{[[} operators, except that
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  equivalent to the \code{[} and \code{[[} operators, except that
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  methods dispatch does not take place.  This is to avoid expensive
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  methods dispatch does not take place.  This is to avoid expensive
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  unclassing when applying the default method to an object.  They
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  unclassing when applying the default method to an object.  They
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  should not normally be invoked by end users.
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  should not normally be invoked by end users.
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  As from \R 1.9.0 both \code{$} and \code{[[} can be applied to
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  environments. Only character arguments are allowed and no partial
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  matching is done (this is in contrast to the behavior for lists). The
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  semantics of these operations is basically that of \code{get(i, env=x,
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    inherits=FALSE)}. If no match is found then \code{NULL} is
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  returned. The assignment versions, \code{$<-} and
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  \code{[[<-}, can also be used. Again, only character arguments are
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  allowed and no partial matching is done. The semantics in this case
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  are those of \code{assign(i, value, env=x, inherits=FALSE)}. Such an
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  assignment will either create a new binding or change the existing
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  binding in \code{x}.
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}
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}
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\references{
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\references{
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  Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988)
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  Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988)
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  \emph{The New S Language}.
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  \emph{The New S Language}.
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  Wadsworth \& Brooks/Cole.
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  Wadsworth \& Brooks/Cole.
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unlist(z)
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unlist(z)
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z[[c(1, 2)]]
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z[[c(1, 2)]]
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z[[c(1, 2, 1)]]  # both "hello"
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z[[c(1, 2, 1)]]  # both "hello"
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z[[c("a", "b")]] <- "new"
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z[[c("a", "b")]] <- "new"
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unlist(z)
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unlist(z)
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##check $ and [[ for environments
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e1 <- new.env()
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e1$a <- 10
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e1[["a"]]
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e1[["b"]] <- 20
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e1$b
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ls(e1)
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}
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}
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\keyword{array}
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\keyword{array}
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\keyword{list}
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\keyword{list}