R資料類型_R

Vector

> c(2,3,5.5,7.1,2.1,3)[1] 2.0 3.0 5.5 7.1 2.1 3.0> assign("v",c(2,3,5.5,7.1,2.1,3))> v <- 1:10> v [1]  1  2  3  4  5  6  7  8  9 10> rep(2,10) [1] 2 2 2 2 2 2 2 2 2 2> seq(1,5,by=0.5)[1] 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0> seq(length=10,from=1,by=0.5) [1] 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5> v[3][1] 3> v + 1/v + 5 [1]  7.000000  7.500000  8.333333  9.250000 10.200000 11.166667 12.142857 13.125000 14.111111 15.100000> is.vector(v)[1] TRUE

Array

> array(1:9)[1] 1 2 3 4 5 6 7 8 9> array(1:9,dim=c(3,3))     [,1] [,2] [,3][1,]    1    4    7[2,]    2    5    8[3,]    3    6    9> x <- 1:64> dim(x) <- c(2,4,8) #dim() converts the vector into array> is.array(x)[1] TRUE> x[1,,]     [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8][1,]    1    9   17   25   33   41   49   57[2,]    3   11   19   27   35   43   51   59[3,]    5   13   21   29   37   45   53   61[4,]    7   15   23   31   39   47   55   63> dim(x)[1] 2 4 8> dim(x)[1][1] 2> dim(x)[2][1] 4> dim(x)[3][1] 8

Data Frame

> x <- BOD> is.matrix(x)[1] FALSE> is.data.frame(x)[1] TRUE> x  Time demand1    1    8.32    2   10.33    3   19.04    4   16.05    5   15.66    7   19.8> y <- x[2,]> is.list(y)[1] TRUE> is.data.frame(y)[1] TRUE> x$Time[1] 1 2 3 4 5 7> x$demand[1]  8.3 10.3 19.0 16.0 15.6 19.8

判斷一個frame裡面是否包含某個值

> frame <- data.frame(x=c(1,2,3),y=c(4,5,6))> 3 %in% frame$x[1] TRUE> 3 %in% frame$y[1] FALSE> c(1,3) %in% frame$x[1] TRUE TRUE

Factor

> v <- c(1,3,5,8,2,1,3,5,3,5)> factor(v) [1] 1 3 5 8 2 1 3 5 3 5Levels: 1 2 3 5 8> factor(v, levels=c(2,1)) [1] 1    <NA> <NA> <NA> 2    1    <NA> <NA> <NA> <NA>Levels: 2 1> levels(x) <- c("two","one")

Matrix

> matrix(c(3,5,7,1,9,4),nrow=3,ncol=2,byrow=TRUE)     [,1] [,2][1,]    3    5[2,]    7    1[3,]    9    4#用which返回數組下標>a=c(1,3,4,5,3,2,5,6,3,2,5,6,7,5,8)#取數組a中最大值的下標>which.max(a)[1] 15#取數組a中最小值的下標>which.min(a)[1] 1#取數組a中大於3值的下標>which(a>3)[1] 3 4 7 8 11 12 13 14 15#取數組a中等於3值的下標>which(a==3)[1] 2 5 9

Matrix與Vector之間的關係

> v1 <- rnorm(5)> v2 <- rnorm(5)> v3 <- rnorm(5)> v1[1] -0.09606998  0.20435991 -2.05094095 -0.86723059 -0.03072555> mat <- matrix(c(v1,v2),nrow=length(v1))> mat <- cbind(mat,v3)  #append by column would be cbind (column bind)> mat                                     v3[1,] -0.09606998  1.8699476 -0.06645094[2,]  0.20435991 -0.2373573  0.27731764[3,] -2.05094095 -0.7309495  0.05417499[4,] -0.86723059 -1.6340647  0.81153156[5,] -0.03072555  0.2326525  0.93222996