| 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 interpretation of the unnamed arguments of seq is
not standard, and it is recommended to always name the
arguments when programming.
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), unless the argument is of length 1 when it is
interpreted as a length argument.
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 1e-14
times the larger of the ends) will return from.
Value
The result is of mode "integer" if from is
(numerically equal to an) integer and by is not specified.
References
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth \& Brooks/Cole.
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)
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