seq {base} | R Documentation |

Generate regular sequences.

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

`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. |

`a,b` |
`factor` s of same length. |

The binary operator `:`

has two meanings: for factors `a:b`

is
equivalent to `interaction(a, b)`

(except for labelling by
`la:lb`

not `la.lb`

). For numeric arguments `a:b`

is
equivalent to `seq(from=a, to=b)`

.

The interpretation of the unnamed arguments of `seq`

is
*not* standard, and it is recommended always to name the
arguments when programming.

Function `seq`

is generic, and only the default method is
described here.

The operator `:`

and the `seq(from, to)`

form generate the
sequence `from, from+1, ..., to`

.

The second form generates `from, from+by`

, ..., up to the
sequence value less than or equal to `to`

.

The third generates a sequence of `length`

equally spaced values
from `from`

to `to`

.

The fourth form generates the sequence `1, 2, ..., length(along)`

.

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

(as if argument `along`

had been specified),
*unless* the argument is numeric of length 1 when it is
interpreted as `1:from`

(even for `seq(0)`

for
compatibility with S).

If `from`

and `to`

are factors of the same length, then
`from : to`

returns the “cross” of the two.

Very small sequences (with `from - to`

of the order of *10^{-14}*
times the larger of the ends) will return `from`

.

The result is of `mode`

`"integer"`

if `from`

is
(numerically equal to an) integer and `by`

is not specified.

Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988)
*The New S Language*.
Wadsworth & Brooks/Cole.

The method `seq.POSIXt`

.

As an alternative to using `:`

for factors, `interaction`

.

1:4 pi:6 # float 6:pi # integer seq(0,1, length=11) 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) seq(17) # same as 1:17 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