seq {base} | R Documentation |
Generate regular sequences. seq
is a standard generic with a
default method. seq.int
is an internal generic which can be
much faster but has a few restrictions. seq_along
and
seq_len
are very fast primitives for two common cases.
seq(...) ## Default S3 method: seq(from = 1, to = 1, by = ((to - from)/(length.out - 1)), length.out = NULL, along.with = NULL, ...) seq.int(from, to, by, length.out, along.with, ...) seq_along(along.with) seq_len(length.out)
... |
arguments passed to or from methods. |
from, to |
the starting and (maximal) end value of the sequence. |
by |
number: increment of the sequence. |
length.out |
desired length of the sequence. A
non-negative number, which for seq and seq.int will be
rounded up if fractional. |
along.with |
take the length from the length of this argument. |
The interpretation of the unnamed arguments of seq
and
seq.int
is not standard, and it is recommended always to
name the arguments when programming.
Both seq
are seq.int
are generic, and only the default
method is described here. Typical usages are
seq(from, to) seq(from, to, by= ) seq(from, to, length.out= ) seq(along.with= ) seq(from) seq(length.out= )The first form generates the sequence
from, from+/-1, ..., to
(identical to from:to
).
The second form generates from, from+by
, ..., up to the
sequence value less than or equal to to
. Specifying
to - from
and by
of opposite signs is an error. Note
that the computed final value can go just beyond to
to allow for
rounding error, but (as from R 2.9.0) is truncated to to
.
(‘Just beyond’ is by up to 1e-10 times
abs(from - to)
as from R 2.11.0: previously it was
1e-7 times.)
The third generates a sequence of length.out
equally spaced
values from from
to to
. (length.out
is usually
abbreviated to length
or len
, and seq_len
is much
faster.)
The fourth form generates the integer sequence 1, 2, ...,
length(along.with)
. (along.with
is usually abbreviated to
along
, and seq_along
is much faster.)
The fifth form generates the sequence 1, 2, ..., length(from)
(as if argument along.with
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).
The final form generates the integer sequence 1, 2, ...,
length.out
unless length.out = 0
, when it generates
integer(0)
.
Very small sequences (with from - to
of the order of 10^{-14}
times the larger of the ends) will return from
.
For seq
(only), up to two of from
, to
and
by
can be supplied as complex values provided length.out
or along.with
is specified.
seq.int
, seq_along
and seq_len
are
primitive.
seq.int
and the default method of seq
return a vector of
type "integer"
or "double"
: programmers should not rely
on which.
seq_along
and seq_length
always return an integer vector.
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
The methods seq.Date
and seq.POSIXt
.
seq(0, 1, length.out=11) seq(stats::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