bdVector of evenly spaced numbers. The start, end, spacing, and length of the sequence can be specified.
Methods). Method functions can be written to handle specific S Version 3 classes of data. Classes which already have methods for this function include
dates.
seq(...)
seq.default(from=<<see below>>, to=<<see below>>,
by=<<see below>>, length.out=<<see below>>, along.with=NULL, bigdata=F)
from:to # the operator
: (the colon operator). If
to,
by, and
length are all given, the value for
from is inferred. Otherwise, the default is
1.
: (the colon operator). If
from,
by, and
length are all given, the value for
to is inferred. Otherwise, the default is
1. A value of
to that is less than
from is allowed.
from,
to, and
length are all given, the value for
by is inferred. Otherwise, the default is
1.
from,
to, and
by are all given, the value for
length is inferred.
TRUE, an object of type
bdVector is returned.
Otherwise, a
vector object is returned. This argument can be used only if the bigdata library section has been loaded.
bdVector with values (
from,
from+by,
from+2*by, ...,
to).
from value may be larger or smaller than the
to value. If
by is specified, it must have the appropriate sign for a finite sequence to be generated; i.e.,
by must be negative if
from is larger than
to. If the difference between
from and
to is not a multiple of
by, the sequence stops at the last value that is not past
to.
If
seq is called with one unnamed, numeric argument of length 1, an integer sequence from 1 to the value of the argument is returned. For example, the command
seq(4) returns the integers 1, 2, 3, 4.
To generate an integer sequence from 1 to
length(x) for an object
x, use one of the following commands:
seq(along=x),
seq(x), or
1:length(x). If
x has length 0 or 1,
seq(along=x) produces a sequence of length 0 or 1, while
seq(x) returns the integer sequence from 1 to
x.
The colon operator has a high precedence (see the help file for
Syntax). Thus, for example, parentheses are needed to create a sequence from
1 to
n-1: use the command
1:(n-1) instead of
1:n-1.
If
by is very small and
to is specified, the final element in the returned sequence may not equal
to (although it will be extremely close).
This is due to finite precision arithmetic, which you can work around with a different choice of operators.
For example, the sequence produced by
seq(0,1,by=1/n) may not end exactly at 1 if
n is very large.
Instead, you can use the commands
seq(0,1,length=n+1) or
0:n/n to create a sequence that ends in 1.
# Two ways to obtain the sequence 1, 2, 3, 4, 5. seq(5) 1:5 # The sequence 5, 4, 3, 2, 1. 5:1 # Integer sequence from 1 to -5. seq(-5) # The sequence 1.1, 2.1, 3.1, 4.1. 1.1 : 5 # The sequence 0, 0.01, 0.02, ..., 1. seq(0, 1, by=0.01) # 100 values from -pi to pi. seq(-pi, pi, length=100)