https://www.cnblogs.com/zhangduo/p/4537168.html 基本操作 用all.equal函数检查浮点数是否相等,容忍度默认为1.5e-8,如果相等返回TRUE,不相等返回差值。将其嵌入isTRUE函数则返回TRUE或者FALSE 使用<<-对全局变量赋值,或者使用assign函数,参数:“变量名”,值,如果全局赋值加上globalenv()参数。assign函数高级用法,需少用。 一般直接输入变量名就会输出结果,是为隐式调用print函数,从linux终端运行等需要加上print函数。 特殊数字:Inf,-Inf,NaN,NA。NaN(not a number),NA(not available)代表缺失值。is.finite函数检查特殊数字,正常数字返回TRUE,is.infinite函数相反。is.nan函数检查NaN,is.na函数检查NA,NaN。 三种逻辑:TRUE,FALSE,NA。any和all函数检查逻辑向量 NULL是个特殊值,表示空的变量。NULL没有长度,用is.null来测试,把某个元素设置为NULL为删除,它因此采用list(NULL)来设置。 head函数可显示前几行(默认为6行),head('',n)显示前n行。 工作目录:查看getwd(),更改setwd("path")。绝对路径的书写用/书写,windows下可以用\\,为了在各个系统下保持一致,尽量用/间隔 清除工作区的变量
1 2 3 4 5 6 7 8 | #清除所有变量
rm (list= ls ())
#清除单个变量
rm (data)
#清除多个变量
rm (list= c ( 'data1' , 'data2' ))
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1 2 3 4 5 | > str (a)
'data.frame' : 13 obs. of 3 variables:
$ class: Factor w/ 7 levels "浜岀彮" , "涓夌彮" ,..: 7 6 5 4 3 1 1 1 1 2 ...
$ name : Factor w/ 10 levels "" , "122" , "闄堜附鐏\xb5,115" ,..: 1 2 1 1 2 8 7 6 5 4 ...
$ score: int NA NA NA NA NA 119 96 NA NA NA ...
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1 2 3 4 5 6 7 8 9 | > attributes (a)
$names
[1] "class" "name" "score"
$class
[1] "data.frame"
$row.names
[1] 1 2 3 4 5 6 7 8 9 10 11 12 13
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生成数据1 2 3 4 5 6 7 8 9 10 11 12 | > vector ( 'numeric' ,5) #numeric(5)
[1] 0 0 0 0 0
> vector ( 'logical' ,5) #logical(5)
[1] FALSE FALSE FALSE FALSE FALSE
> vector ( 'character' ,5) #character(5)
[1] "" "" "" "" ""
> vector ( 'list' ,2)
[[1]]
NULL
[[2]]
NULL
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1 2 3 4 5 6 7 8 | > letters [4]
[1] "d"
> letters [1:4]
[1] "a" "b" "c" "d"
> letters []
[1] "a" "b" "c" "d" "e" "f" "g" "h" "i" "j" "k" "l"
[13] "m" "n" "o" "p" "q" "r" "s" "t" "u" "v" "w" "x"
[25] "y" "z"
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1 2 3 4 5 6 7 8 9 10 11 | #runif(n,min,max),默认产生0-1之间的随机数
> runif (3)
[1] 0.3308360 0.5573855 0.9720616
> runif (3,min=1,max=9)
[1] 8.946071 4.915268 5.763918
#rnom可指定参数mean:平均数,sd:标准差,默认mean=0,sd=1
> rnorm (5)
[1] 0.55080064 -0.24792330 -0.09480838 0.65215600
[5] -0.96422061
> rnorm (5,mean=2,sd=0.3)
[1] 2.373522 2.176204 1.948216 2.371155 2.070872
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | #seq.int创建一个序列,与冒号有所不同,指定步长时也不一样
> 2:8
[1] 2 3 4 5 6 7 8
> seq.int (2:8)
[1] 1 2 3 4 5 6 7
> seq.int (4,10,3) #指定步长3
[1] 4 7 10
#seq_len函数创建一个从1到它的输入值的序列,输入为0时创建一个空值
> seq_len (0)
integer (0)
> attributes ( seq_len (0))
NULL
#seq_along创建一个从1开始、长度为其输入值的序列
> seq_along ( letters [1:10])
[1] 1 2 3 4 5 6 7 8 9 10
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1 2 3 4 5 6 7 8 9 10 11 12 | #整体重复三遍
> rep (1:5,3)
[1] 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
#每个元素重复三遍
> rep (1:5,each=3)
[1] 1 1 1 2 2 2 3 3 3 4 4 4 5 5 5
#每个元素重复个数:1:5
> rep (1:5,times=1:5)
[1] 1 2 2 3 3 3 4 4 4 4 5 5 5 5 5
#重复矢量直到达到15的长度
> rep (1:5,length.out=15)
[1] 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 | #array创建数组,另个参数:值,维度dim
> array (1:12,dim= c (3,4))
[,1] [,2] [,3] [,4]
[1,] 1 4 7 10
[2,] 2 5 8 11
[3,] 3 6 9 12
#matrix创建矩阵,需要指定行数或者列数,默认输入的值按照列填充,或者指定参数byrow=TRUE按行填充
> matrix (1:12,nrow=3)
[,1] [,2] [,3] [,4]
[1,] 1 4 7 10
[2,] 2 5 8 11
[3,] 3 6 9 12
> matrix (1:12,nrow=3,byrow= TRUE )
[,1] [,2] [,3] [,4]
[1,] 1 2 3 4
[2,] 5 6 7 8
[3,] 9 10 11 12
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向量,矩阵和数组1.length函数1 2 3 4 5 6 7 8 9 10 11 | > length (1:5)
[1] 5
#缺失值NA也被计入长度
> length ( c ( TRUE , FALSE , NA ))
[1] 3
#返回字符串的数目
> length ( c ( 'A' , 'B' , 'C' ))
[1] 3
#若想返回每个字符串中字符的长度用nchar
> nchar ( c ( 'Axc' , 'Bcdsfs' , 'Cdsss' ))
[1] 3 6 5
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若用于矩阵和数组则返回所有维度的乘积 2.命名name可以在创建数据时指定名称,也可以在事后命名。 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 | #kiwi fruit用引号括起来了,因为其名称无效:有空格
#可以忽略其他元素命名
> c (apple=1, "kiwi fruit" =2,3)
apple kiwi fruit
1 2 3
> x <- 1:3
> names (x) <- c ( "apple" , "kiwi fruit" , '' )
> x
apple kiwi fruit
1 2 3
#names函数返回名称,若没有一个元素有名字则返回NULL
> names (x)
[1] "apple" "kiwi fruit" ""
> names(1:4)
NULL
#创建数组时命名,矩阵同样
> x <- array (1:6,dim= c (2,3),dimnames= list ( c ( "one" , "tow" ), c ( "ein" , "zwei" , "drei" )))
> x
ein zwei drei
one 1 3 5
tow 2 4 6
#rownames、colnames和dimnames函数
> rownames (x)
[1] "one" "tow"
> colnames (x)
[1] "ein" "zwei" "drei"
> dimnames (x)
[[1]]
[1] "one" "tow"
[[2]]
[1] "ein" "zwei" "drei"
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3.行、列和维度dim函数对于数组和矩阵返回所有维度。nrow和ncol函数分别返回行和列。norm、ncol和dim用于向量时返回NULL。NROW和NCOL函数把向量看做列向量 4.合并矩阵c函数拼接矩阵把他们转换成向量,cbind和rbind分别按col列和row行合并矩阵 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 | > x <- matrix (1:12,nrow=3);x
[,1] [,2] [,3] [,4]
[1,] 1 4 7 10
[2,] 2 5 8 11
[3,] 3 6 9 12
> y <- matrix (13:24,nrow=3);y
[,1] [,2] [,3] [,4]
[1,] 13 16 19 22
[2,] 14 17 20 23
[3,] 15 18 21 24
> c (x,y)
[1] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
[17] 17 18 19 20 21 22 23 24
> cbind (x,y)
[,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8]
[1,] 1 4 7 10 13 16 19 22
[2,] 2 5 8 11 14 17 20 23
[3,] 3 6 9 12 15 18 21 24
> rbind (x,y)
[,1] [,2] [,3] [,4]
[1,] 1 4 7 10
[2,] 2 5 8 11
[3,] 3 6 9 12
[4,] 13 16 19 22
[5,] 14 17 20 23
[6,] 15 18 21 24
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5.数学运算除法/,转置t函数,点乘%*%和外乘%o%。solve矩阵求反 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 | 向量内乘
> 1:3%*%2:4
[,1]
[1,] 20
#向量外乘
> 1:3%o%2:4
[,1] [,2] [,3]
[1,] 2 3 4
[2,] 4 6 8
[3,] 6 9 12
> x<- matrix (1:6,nrow=2);x
[,1] [,2] [,3]
[1,] 1 3 5
[2,] 2 4 6
> y<- matrix (1:6,nrow=3);y
[,1] [,2]
[1,] 1 4
[2,] 2 5
[3,] 3 6
#矩阵相乘
> x%*%y
[,1] [,2]
[1,] 22 49
[2,] 28 64
> x<- matrix ( runif (9),nrow=3);x
[,1] [,2] [,3]
[1,] 0.6136448 0.05304645 0.7378249
[2,] 0.1922476 0.18177634 0.9545918
[3,] 0.9050422 0.65400112 0.2954112
#矩阵求逆
> solve (x)
[,1] [,2] [,3]
[1,] 1.6984882 -1.389698 0.2484943
[2,] -2.4026083 1.448092 1.3214365
[3,] 0.1154494 1.051693 -0.3016769
#矩阵转置
> t (x)
[,1] [,2] [,3]
[1,] 0.98387863 0.6292973 0.03753178
[2,] 0.09061386 0.5971163 0.10537436
[3,] 0.80727162 0.5403768 0.55767250
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