1、seq()

用來生成一組數字的函數。

Usage：

## 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：

... ：?arguments passed to or from methods.

from, to ： the starting and (maximal) end values of the sequence. Of length 1 unless just

from ： is supplied as an unnamed argument.

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.

Typical usages are

seq(from, to)

seq(from, to, by= )

seq(from, to, length.out= )

seq(along.with= )

seq(from)

seq(length.out= )

Examples：

seq(0, 1, length.out = 11)

seq(stats::rnorm(20)) # effectively ‘along‘

seq(1, 9, by = 2) # matches ‘end‘

seq(1, 9, by = pi) # stays below ‘end‘

seq(1, 6, by = 3)

seq(1.575, 5.125, by = 0.05)

seq(17) # same as 1:17, or even better seq_len(17)

原文：http://www.cnblogs.com/nanhao/p/6668289.html