phep toan thong thuong

1+2 3+3 4/3

chia lay phan nguyen

7 %/% 3

chia lay du

7 %% 3

#them L de chuyen sang kieu int class(4L) class(3**6)

binh phuong: ^ or **

3^6 3**6

print

“hello world”

phep gan

y<-“hola” y # cho vao () de print gia tri duoc gan luon (y <- “visible”)

length: dem so phan tu trong 1 vecto

x=1:36 x length(x) length(“hola”) length(c(“du ma”,“sida”)) #them c o trc de noi 2 vecto

nchar: dem so ki tu

nchar(“1234 holisit”) # do do dai chuoi

lay ptu o vi tri [i]

(v<-1:18) v[12]

hien ptu o vi tri a->b: x[a,b]

n<-c(“hello”,“siba”,“a”,“b”,“C”)

n[1:3] #hien thi ptu o vitri 1>3

hien ptu o vi tri a,b,.. : x[c(a,b)]

n[c(2,4)] #hien thi ptu o vitri 2,4

v%%2==0

v[v%%2==0] #hien gia tri cac ptu chia cho 2

v[v%%3==0]

gan ten:

p <- c(“A” = 1, “B” = 2, “C” = 3) #gan ten

p

names(p)<-c(“ten 1”,“ten 2”,“ten 3”) #van la gan ten

p

x<-1:4 y<-3:6

x^2-y

vi du function

ham_mu3_tong<-function(m,n){

mu_3<-m*3

mu_3+n }

ham_mu3_tong(1:3,c(7,3,1)) #truyen tham so

mean: ham tinh tbinh cong

chuoi<-1:36

mean(chuoi) #ham tinh trung binh cong

if eo

t<-4

if(t<2) (“sai”) else (“wowowowowo”)

cau truc ifelse : dung khi bai toan la mot vecto(vecto hoa)

t<-4

p=c(1,4,7)

ifelse(t>p,(“meo”),(“gau”)) # ifelse(test, yes, no)

vecto hoa (vectorize)

cach 1:gan Vectorize de khi truyen vecto ko bi loi

ham <- function(x) { if (x %% 2 == 0) { x ** 2 } else { x } } ham <- Vectorize(ham)

ham(1:5)

cach 2: dung ifelse

ham_1<-function(x) ifelse(x %%2 == 0,x^2,x) ham_1(1:5)

cau truc for

rauma<-c(“bo”,“re”,“hdpe”,“thi”,“ngon”,“luon”) for(i in rauma){ if(nchar(i) >=3){ print(i) } }

for(i in x) : duyet theo gia tri

wtf<-c(1,4,6) tong_1<-0 for(i in wtf) tong_1<-tong_1+i # duyet gia tri tong_1

for(i in seq_along(x)) : duyet theo vi tri

tong_2<-0 for(i in seq_along(wtf)) tong_2<-tong_2+i # “seq_along” duyet chi so tong_2