| 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 |
factors 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