R: Sequence Generation

seq {base} | R Documentation

## Sequence Generation

### Description

Generate regular sequences.

### Usage

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

### Arguments

`from` | starting value of sequence.
`to` | (maximal) end value of the sequence.
`by` | increment of the sequence.
`length` | desired length of the sequence.
`along` | take the length from the length of this argument.

### 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 and `by` is not specified.

### 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)
    stopifnot(
     3 == seq(3,3,  by=pi),
     3 == seq(3,3.1,by=pi),
     seq(1,6,by=3) == c(1,4),
     seq(10,4.05,by=-3) == c(10,7)
    )

    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

[Package Contents]