Demo20200624

R 範例

data(anscombe)
View(anscombe)
plot(y1 ~ x1, data = anscombe)
lmfit<- lm(y1 ~ x1, data = anscombe)
lmfit
plot(y1 ~ x1, data = anscombe)
abline(lmfit, col='red')

Ｒ基礎

3 + 8 
3 - 8
5 * 5
11 / 2
2 ^ 10
11 %% 2

a <- 3
b = 5
c <- a + b

numer <-  17.8
char <- "hello world"
logic <- TRUE

class(numer)
class(char)
class(logic)

card_length <- 3
card_width <- "5 inches"

#card_length * card_width


card_width <- 5
card_length * card_width

1 - (40 / 100)

R向量

height_vec  <- c(180,169,173)
height_vec
name_vec <- c('Brian', 'Toby', 'Sherry')

a <- 1
a <- c(1)

x <- c(1,2,3,4)
y <- c(2,3,4,5)

x + y
x - y 
x * y
x / y

x <- c(1,2,3,4)
y <- c(3,5)
x + y

x <- 1:20
x

y <- seq(1,20)
y

?seq
help(seq)
seq(1,20,2)
seq(1,3.5, by = 0.5)
seq(1,10,length.out = 2)
seq(1,10,lengt = 2)


x <- c(1,2,3,5,7) 
sum(x)
?sum

NaN
x <- c(1,2,3,5,7,NaN) 
sum(x)
sum(x, na.rm=TRUE)

height_vec <- c(180,169,173)
name_vec <- c("Brian", "Toby", "Sherry")

names(height_vec)
names(height_vec) <- name_vec
height_vec
names(height_vec)

height_vec > 175
height_vec < 175
height_vec >= 175
height_vec <= 175
height_vec == 180
height_vec != 180

height_vec >=170  &  height_vec < 180
height_vec < 170  |  height_vec >= 180
(! ( height_vec >=170  &  height_vec < 180 ))

height_vec > 175
height_vec[height_vec > 175]

height_vec <- c(180,169,173)
weight_vec <- c(73, 87, 43)
name_vec <- c('Brian','Toby', 'Sherry')
bmi_vec <- weight_vec / (height_vec / 100) ^2 
names(bmi_vec) <- name_vec
bmi_vec

bmi_vec[bmi_vec <= 18.5 | bmi_vec >= 24]

names(bmi_vec[bmi_vec <= 18.5 | bmi_vec >= 24])

bmi_cal <- function(bmi){
  if(bmi < 18.5){
    return('體重過輕')
  }else if (bmi >= 18.5 & bmi < 24){
    return('正常')
  }else{
    return('體重過重')
  }
}
bmi_cal(36)


?apply
lapply(bmi_vec, bmi_cal)
sapply(bmi_vec, bmi_cal)

Ｒ矩陣

kevin   <- c(85,73)
marry   <- c(72,64)
jerry   <- c(59,66)

c(kevin, marry, jerry)
mat <- matrix(c(kevin, marry,jerry), nrow = 3, byrow=TRUE)
mat

matrix(1:9, nrow = 3)
matrix(1:9, nrow = 3, byrow = TRUE)

mat
colnames(mat) <- c('first', 'second')
mat

rownames(mat) <- c('kevin', 'marry', 'jerry')
mat
mat <- matrix(c(kevin, marry, jerry), nrow=3, byrow=TRUE, 
dimnames=list(c('kevin', 'marry', 'jerry'),c('first', 'second')))
mat

dim(mat)
nrow(mat)
ncol(mat)

kevin
kevin[1]
kevin[2]

mat
mat[1,]
mat[,1]
1:9
mat[2:3,]
mat[c(2,3), ]
mat[2,1]
mat2 <- rbind(mat, c(78,63))
mat2
rownames(mat2)[4] <- 'Sam'
mat2
mat3 <- cbind(mat,c(82,77,70))
mat3
colnames(mat3)[3] <- 'third'
mat3

m1 <- matrix(1:4, byrow=TRUE, nrow=2)
m2 <- matrix(5:8, byrow=TRUE, nrow=2)
m1 + m2
m1 - m2
m1 * m2
m1 / m2

mat
rowSums(mat)
colSums(mat)

m1 <- matrix(1:9, nrow = 9)
dim(m1)
m2 <- matrix(1:9, ncol = 9)
dim(m2)
m1 %*% m2