attributes               package:base               R Documentation

Object Attribute Lists

Description:

     These functions access an object's attributes. The first form
     below returns the object's attribute list. The replacement forms
     uses the list on the right-hand side of the assignment as the
     object's attributes (if appropriate).

Usage:

     attributes(obj)
     attributes(obj) <- value
     mostattributes(obj) <- value

Arguments:

     obj: an object

   value: an appropriate named list of attributes, or 'NULL'.

Details:

     Note that some attributes (namely 'class', 'comment', 'dim',
     'dimnames', 'names', (from R 2.4.0) 'row.names' and 'tsp') are
     treated specially and have restrictions on the values which can be
     set.

     Attributes are not stored internally as a list and should be
     thought of as a set and not a vector.  They must have unique names
     (and 'NA' is taken as '"NA"', not a missing value).

     The 'mostattributes' assignment takes special care for the 'dim',
     'names' and 'dimnames' attributes, and assigns them only when
     valid whereas an 'attributes' assignment would give an error if
     any are not.

     The names of a pairlist are not stored as attributes, but are
     reported as if they were (and can be set by the replacement method
     for attributes).

References:

     Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) _The New S
     Language_. Wadsworth & Brooks/Cole.

See Also:

     'attr'.

Examples:

     x <- cbind(a=1:3, pi=pi) # simple matrix w/ dimnames
     attributes(x)

     ## strip an object's attributes:
     attributes(x) <- NULL
     x # now just a vector of length 6

     mostattributes(x) <- list(mycomment = "really special", dim = 3:2,
        dimnames = list(LETTERS[1:3], letters[1:5]), names = paste(1:6))
     x # dim(), but not {dim}names

