Colon {base}R Documentation

Colon Operator

Description

Generate regular sequences.

Usage

from:to
   a:b

Arguments

from starting value of sequence.
to (maximal) end value of the sequence.
a, b factors of same length.

Details

The binary operator : has two meanings: for factors a:b is equivalent to interaction(a, b) (but the levels are ordered and labelled differently).

For numeric arguments from:to is equivalent to seq(from, to), and generates a sequence from from to to in steps of 1 or 1-. Value to will be included if it differs from from by an integer up to a numeric fuzz of about 1e-7.

Value

For numeric arguments, a numeric vector. This will be of type integer if from is integer-valued and the result is representable in the integer type, otherwise of type "double" (aka mode "numeric").

For factors, an unordered factor with levels labelled as la:lb and ordered lexicographically (that is, lb varies fastest).

References

Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
(for numeric arguments: S does not have : for factors.)

See Also

seq.

As an alternative to using : for factors, interaction.

For : used in the formal representation of an interaction, see formula.

Examples

1:4
pi:6 # real
6:pi # integer

f1 <- gl(2,3); f1
f2 <- gl(3,2); f2
f1:f2 # a factor, the "cross"  f1 x f2

[Package base version 2.11.0 Index]