Syntax: Operator Syntax and Precedence

Description

Outlines R syntax and gives the precedence of operators.

Arguments

Details

The following unary and binary operators are defined. They are listed in precedence groups, from highest to lowest.

:: :::

access variables in a namespace

$ @

component / slot extraction

[ [[

indexing

^

exponentiation (right to left)

- +

unary minus and plus

:

sequence operator

%any%

special operators (including %% and %/%)

* /

multiply, divide

+ -

(binary) add, subtract

< > <=>= == !=

ordering and comparison

!

negation

& &&

and

| ||

~

as in formulae

-> ->>

rightwards assignment

<- <<-< code="">

assignment (right to left)

=

assignment (right to left)

?

help (unary and binary)

Within an expression operators of equal precedence are evaluated from left to right except where indicated. (Note that = is not necessarily an operator.)

The binary operators ::, :::, $ and @ require names or string constants on the right hand side, and the first two also require them on the left.

The links in the See Also section cover most other aspects of the basic syntax.

References

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