as.list(x, …) # S3 method for environment as.list(x, all.names = FALSE, sorted = FALSE, …) as.pairlist(x)
namesof the resulting list should be sorted (increasingly). Note that this is somewhat costly, but may be useful for comparison of environments.
formalsof functions). The arguments to
pairlistare of the form
tag = value. The functions return a list or dotted pair list composed of its arguments with each value either tagged or untagged, depending on how the argument was specified.
alisthandles its arguments as if they described function arguments. So the values are not evaluated, and tagged arguments with no value are allowed whereas
listsimply ignores them.
alistis most often used in conjunction with
as.listattempts to coerce its argument to a list. For functions, this returns the concatenation of the list of formal arguments and the function body. For expressions, the list of constituent elements is returned.
as.listis generic, and as the default method calls
as.vector(mode = "list")for a non-list, methods for
as.vectormay be invoked.
as.listturns a factor into a list of one-element factors. Attributes may be dropped unless the argument already is a list or expression. (This is inconsistent with functions such as
as.characterwhich always drop attributes, and is for efficiency since lists can be expensive to copy.)
TRUEif and only if its argument is a
TRUEif and only if the argument is a pairlist or
NULL(see below). The
as.listcopies the name-value pairs (for names not beginning with a dot) from an environment to a named list. The user can request that all named objects are copied. Unless
sorted = TRUE, the list is in no particular order (the order depends on the order of creation of objects and whether the environment is hashed). No enclosing environments are searched. (Objects copied are duplicated so this can be an expensive operation.) Note that there is an inverse operation, the
as.environment()method for list objects. An empty pairlist,
pairlist()is the same as
NULL. This is different from
list(): some but not all operations will promote an empty pairlist to an empty list.
as.pairlistis implemented as
as.vector(x, "pairlist"), and hence will dispatch methods for the generic function
as.vector. Lists are copied element-by-element into a pairlist and the names of the list used as tags for the pairlist: the return value for other types of argument is undocumented.
is.pairlistare primitive functions.
vector("list", length)for creation of a list with empty components;
c, for concatenation;
unlistis an approximate inverse to
as.list(). ‘plotmath’ for the use of
listin plot annotation.
require(graphics) # create a plotting structure pts <- list(x = cars[,1], y = cars[,2]) plot(pts) is.pairlist(.Options) # a user-level pairlist ## "pre-allocate" an empty list of length 5 vector("list", 5) # Argument lists f <- function() x # Note the specification of a "..." argument: formals(f) <- al <- alist(x = , y = 2+3, … = ) f al ## environment->list coercion e1 <- new.env() e1$a <- 10 e1$b <- 20 as.list(e1)
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