expression
Expression Objects

Description

Creates or tests for objects of mode expression.

Usage

expression(...)
is.expression(x)
as.expression(x)
## Default S3 method:
as.expression(x)

Arguments

... any valid expression. Not evaluated by the call to expression.
x any object.

Details

as.expression is a generic function, but currently there is only the default method.
Value
expressionreturns an expression; that is, a list-like object of mode "expression". Its elements are the arguments, unsubstituted and unevaluated.
is.expressionreturns TRUE if x has mode "expression". Otherwise it returns FALSE.
as.expressionchanges the mode of x to "expression".
Background
The output from parse is of mode "expression".
References
Becker, R. A., Chambers, J. M., and Wilks, A. R. 1988. The New S Language. Pacific Grove, CA: Wadsworth & Brooks/Cole Advanced Books and Software.
See Also
eval, parse, substitute.
Examples
x<-c(1,2,3)
y<-c(2,4,6)
mymethod <- expression(lsfit(x,y), rexp(1))
eval(mymethod[[which(x == 1)]])

rand.choice <- expression("Gaussian"=rnorm(1),"exp"=rexp(1), "uniform"=runif(1)) eval(rand.choice[["exp"]])

Package base version 6.1.4-13
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