| 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 |
|
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 and to are both integers
and representable in the integer type, otherwise of type
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