| assignOps {base} | R Documentation |
Assign a value to a name.
x <- value x <<- value value -> x value ->> x x = value
x |
a variable name (possibly quoted). |
value |
a value to be assigned to x. |
There are three different assignment operators: two of them have leftwards and rightwards forms.
The operators <- and = assign into the environment in
which they are evaluated. The operator<- can be used
anywhere, whereas the operator = is only allowed at the top
level (e.g., in the complete expression typed at the command prompt)
or as one of the subexpressions in a braced list of expressions.
The operators <<- and ->> cause a search to made through
the environment for an existing definition of the variable being
assigned. If such a variable is found then its value is redefined,
otherwise assignment takes place globally. Note that their semantics
differ from that in the S language, but are useful in conjunction with
the scoping rules of R. See ‘The R Language Definition’
manual for further details and examples.
In all the assignment operator expressions, x can be a name
or an expression defining a part of an object to be replaced (e.g.,
z[[1]]). The name does not need to be quoted, though it can
be.
The leftwards forms of assignment <- = <<- group right to left,
the other from left to right.
value. Thus one can use a <- b <- c <- 6.
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
Chamber, J. M. (1998)
Programming with Data. A Guide to the S Language.
Springer (for =).