看到有很多读者浏览了这篇文章,心里很是开心,为了能够更好地帮助大家,决定再修改一下,帮助大家更好地理解。
--------修改于:2018年4月28日
为了方便大家在开发环境中直接实验测试代码,下面,我将说明和函数的用法全部用英文给出(避免乱码),并加以注释,希望能够对大家有所帮助!
首先,我们来看一个seq()函数应用的实例!
x <- seq(0, 10, by = 0.01)
y <- sin(x)
plot(y)
下面,我们来看函数的主要使用方法!
注意:在本文调用函数时,均采用写出入口参数名的方法,比如:
seq(from = 1, to = 2)
这样函数的调用更加清晰,在调用较多函数时,不会发生混乱和参数匹配错误。
方式一:seq(from, to)
from:生成向量的起点,to:生成向量的终点,默认步长为1(可修改)
a <- seq(from = 1, to = 2)
# [1, 2]
方式二:seq(from, to, by = )
by:向量元素之间的步长
a <- seq(from = 1, to = 3, by = 0.5)
# [1, 1.5, 2, 2.5, 3]
方式三:seq(from, to, length.out = )
length.out:向量中元素数目
a <- seq(from = 1, to = 3, length.out = 5)
# [1, 1.5, 2, 2.5, 3]
方式四:seq(along.with = )
along.with:表示生成的向量为现有一向量元素的索引
x <- c(1.2, 5.2, 6.3, 4.6)
a <- seq(along.with = x)
# [1, 2, 3, 4]
方式五:seq(from)
该方式和方式四功能相似
x <- c(1.2, 5.2, 6.3, 4.6)
a <- seq(from = x)
# [1, 2, 3, 4]
方式6:seq(length.out = )
生成从1开始,步长为1,长度为length.out的向量
a <- seq(length.out = 5)
# [1, 2, 3, 4, 5]
上述几种方式为较为常见的方式,详细的函数说明如下:
Sequence Generation
Description
Generate regular sequences. seq is a standard generic with a default method. seq.int is a primitive which can be much faster but has a few restrictions. seq_along and seq_len are very fast primitives for two common cases.
---------------------------------------------
Usage
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
1:...
arguments passed to or from methods.
2:from, to
the starting and (maximal) end values of the sequence. Of length 1 unless just from is supplied as an unnamed argument.
3:by
number: increment of the sequence.
4:length.out
desired length of the sequence. A non-negative number, which for seq and seq.int will be rounded up if fractional.
5:along.with
take the length from the length of this argument.
参考:https://blog.csdn.net/jiluben/article/details/40024607
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