Sequence Generation

Description

Generate regular sequences.

Usage

from:to
seq(from, to)
seq(from, to, by=)
seq(from, to, length=)
seq(along)

Details

The operator : and the first seq(.) form generate the sequence from, from+1, ..., to. seq is a generic function.

The second form generates from, from+by, ..., to.

The third generates a sequence of length equally spaced values from from to to.

The last generates the sequence 1, 2, ..., length(along).

If from and to are factors of the same length, then from : to returns the ``cross'' of the two.

Value

The result is of mode "integer" if from is (numerically equal to an) integer.

See Also

rep, sequence, row, col.

Examples

1:4
pi:6 # float
6:pi # integer

seq(0,1, length=11)
str(seq(rnorm(20)))
seq(1,9, by = 2) # match
seq(1,9, by = pi)# stay below
seq(1,6, by = 3)
seq(1.575, 5.125, by=0.05)


for (x in list(NULL, letters[1:6], list(1,pi)))
  cat("x=",deparse(x),";  seq(along = x):",seq(along = x),"\n")

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