创建因子的函数介绍如下:
factor(x, levels = sort(unique(x), na.last = TRUE),
labels = levels, exclude = NA, ordered = is.ordered(x))
levels 用来指定因子可能的水平(缺省值是向量x中互异的值);labels
用来指定水平的名字;exclude表示从向量x中剔除的水平值;ordered是
一个逻辑型选项用来指定因子的水平是否有次序。回想数值型或字符型
的x。
>factor(1:3)
[1] 1 2 3
Levels: 1 2 3
>factor(1:3, levels=1:5)
[1] 1 2 3
Levels: 1 2 3 4 5
>factor(1:3, labels=c("A", "B", "C"))
[1] A B C
Levels: A B C
>factor(1:5, exclude=4)
[1] 1 2 3 NA 5
Levels: 1 2 3 5
函数levels用来提取一个因子中可能的水平值:
>f <- factor(c(2, 4), levels=2:5)
>f
[1] 2 4
Levels: 2 3 4 5
>levels(f)
[1] "2" "3" "4" "5"
因子用来存储类别变量(categorical variables)和有序变量,这类变量不能用来计算而只能用来分类或者计数。因子表示分类变量,有序因子表示有序变量。生成因子数据对象的函数是factor(),语法是factor(data, levels, labels, ...),其中data是数据,levels是因子水平向量,labels是因子的标签向量。
1、创建一个因子。
例1:
>colour <- c('G', 'G', 'R', 'Y', 'G', 'Y', 'Y', 'R', 'Y')
>col <- factor(colour)
>col1 <- factor(colour, levels = c('G', 'R', 'Y'), labels = c('Green', 'Red', 'Yellow')) #labels的内容替换colour相应位置对应levels的内容
>col2 <- factor(colour, levels = c('G', 'R', 'Y'), labels = c('1', '2', '3'))
>col_vec <- as.vector(col2) #转换成字符向量
>col_num <- as.numeric(col2) #转换成数字向量
>col3 <- factor(colour, levels = c('G', 'R'))
2、创建一个有序因子。
例1:
>score <- c('A', 'B', 'A', 'C', 'B')
>score1 <- ordered(score, levels = c('C', 'B', 'A'))
>score1
[1] A B A C B
Levels: C <B <A
3、用cut()函数将一般的数据转换成因子或有序因子。
例1:
>exam <- c(98, 97, 52, 88, 85, 75, 97, 92, 77, 74, 70, 63, 97, 71, 98,
65, 79, 74, 58, 59, 60, 63, 87, 82, 95, 75, 79, 96, 50, 88)
>exam1 <- cut(exam, breaks = 3) #切分成3组
>exam1
[1] (82,98] (82,98] (50,66] (82,98] (82,98] (66,82] (82,98] (82,98] (66,82]
[10] (66,82] (66,82] (50,66] (82,98] (66,82] (82,98] (50,66] (66,82] (66,82]
[19] (50,66] (50,66] (50,66] (50,66] (82,98] (66,82] (82,98] (66,82] (66,82]
[28] (82,98] (50,66] (82,98]
Levels: (50,66] (66,82] (82,98]
>exam2 <- cut(exam, breaks = c(0, 59, 69, 79, 89, 100)) #切分成自己设置的组
>exam2
[1] (89,100] (89,100] (0,59] (79,89] (79,89] (69,79] (89,100] (89,100]
[9] (69,79] (69,79] (69,79] (59,69] (89,100] (69,79] (89,100] (59,69]
[17] (69,79] (69,79] (0,59] (0,59] (59,69] (59,69] (79,89] (79,89]
[25] (89,100] (69,79] (69,79] (89,100] (0,59] (79,89]
Levels: (0,59] (59,69] (69,79] (79,89] (89,100]
>attr(exam1, 'levels')
[1] "(50,66]" "(66,82]" "(82,98]"
>attr(exam2, 'levels')
[1] "(0,59]" "(59,69]" "(69,79]" "(79,89]" "(89,100]"
>attr(exam2, 'class')
[1] "factor"
#一个有序因子
>x <- factor(rep(1:5,3))
>ordered(x,labels = c('a1','a2','a3','a4','a5'))
[1] a1 a2 a3 a4 a5 a1 a2 a3 a4 a5 a1 a2 a3 a4 a5
Levels: a1 <a2 <a3 <a4 <a5
1、r语言读取txt文件的方法:首先根据下图图片中的命令代码进行输入
2、然后这样就可以读取txt文件了,结果图如下:
3、R读取csv文件的方法:在读取csv文件时,分割符为“,”;可以根据下方的代码进行编辑。
read.csv(file, header = TRUE, sep = ",", quote = "\"",
dec = ".", fill = TRUE, comment.char = "", ...)
4、如果想要读取Excel表格数据的话,可以使用下方的方法来实现。
xls2csv(xls, sheet=1, verbose=FALSE, blank.lines.skip=TRUE, ..., perl="perl")
xls2tab(xls, sheet=1, verbose=FALSE, blank.lines.skip=TRUE, ..., perl="perl")
xls2tsv(xls, sheet=1, verbose=FALSE, blank.lines.skip=TRUE, ..., perl="perl")
xls2sep(xls, sheet=1, verbose=FALSE, blank.lines.skip=TRUE, ...,
method=c("csv","tsv","tab"), perl="perl")
R怎么知道你的文件是放在桌面而不是别的地方。两个办法:
设定工作目录:
setwd("d:/")
然后把txt放在d盘根目录下,用read.table读取
直接把路径带入读入 read.table("d:/exam0203.txt", header=T)
其余的就都解决了吧