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 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

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