R语言语法和Tips

mean(1:3)
1:3

1:5
6:10
1:5+6:10

C(1,3,4,7,8) - 2

1:10%/%3

factorial(5)

-2:2 * -2:2

10%%3


c(1,3,4-1,2+1) ==3

1:3 != 3:1
(1:5)^2 >= 16
sqrt(2)^2 == 2


x<<- sqrt(4)
x
assign("ma_local_variable", 9^3+10^3)
ma_local_variable

x1 = c(1/Inf, Inf/1, Inf/Inf)
x1

x2 = c(NA+1, NA*5, NA+Inf)
x2

(x <- 1:10 >= 5)

(y <- 1:10 %% 2 ==0)

x&y
x|y


none_true <- c(FALSE, FALSE, FALSE)
some_true <- c(FALSE, TRUE, FALSE)
all_true <- c(TRUE, TRUE, TRUE)
any(none_true)
any(some_true)
all(none_true)
all(all_true)


class(1+3i)
class(1L)

gender <- factor(c("female","male"))
gender
class(gender)
levels(gender)
nlevels(gender)
as.integer(gender)





#检查和更改类
if(is(x,"ss")){
  
}

is.character("red lolly")
is.logical(FALSE)
is.list(list(a=1,n=2))

ls(pattern="^is",baseenv())



as.numeric(x)
x <- "123.456"
class(x) <- "numeric"
x


#检查变量或工作区
1+1+1
print(1+1+1)

ulams_spiral <- c(1,8,23,46,77)
for(i in ulams_spiral) i
for(i in ulams_spiral) print(i)

num <- runif(30) #生成随机30个0~1之间的数
num
summary(num)
str(num)
?str


fac <- factor(sample(letters[1:5],30,replace = TRUE))
unclass(fac)
?sample

attributes(fac)



ls()

peach <- 1
plum <- "fruity"
pear <- TRUE
ls()
ls(pattern = "ea")
rm(peach,plum,pear)

# rm(list=ls())








#### 向量 矩阵

c(1:3,c(5:8),13)
vector("numeric",5)
vector("complex",5)
vector("logical",5)
vector("character",5)
numeric(5)
complex(5)
logical(5)
character(5)

seq.int(3,12)
seq.int(3,12,2)
seq_len(5)

pp <- c("fds","fdsfgg","fgserf")
seq_along(pp)

for(i in seq_along(pp)) print(pp[i])



length(1:5)
length(c(TRUE,FALSE,NA))
length(sn)





c(apple=1,banana=2,"kivifruit"=3,4)

x<-1:4
names(x)<-c("apple","banana","kiwifruit")
x


### 索引向量
x<-(1:5)^2
x
x[c(1,3,5)]
x[c(-2,-4)]
x[c(TRUE,FALSE,TRUE,FALSE,TRUE)]


x<-c("one","two","three")
x[]

1:5+1
1+1:5

1:5+1:15

rep(1:5,3)
rep(1:5,each=3)
rep_len(1:5,13)



# 矩阵
a_matrix <- matrix(1:12,nrow=4,dimnames=list(
  c("one","two","three","four"),
  c("ein","zwei","drei")
))
a_matrix

# 二维数组
two_d_arrary<-array(1:12,dim=c(4,3),
             dimnames=list(
              c("one","two","three","four"),
              c("ein","zwei","drei")))
two_d_arrary

dim(two_d_arrary)
dim(a_matrix)
length(two_d_arrary)
length(a_matrix)
rownames(a_matrix)
rownames(two_d_arrary)
colnames(a_matrix)
colnames(two_d_arrary)

a_matrix[1,c("zwei","drei")]
a_matrix[,c("zwei","drei")]
a_matrix[2,]



another_matrix<-matrix(seq.int(2,24,2),
                       nrow=4,
                       dimnames=list(
                         c("five","six","seven","eight"),
                         c("vier","funf","sechs")
                       ))
another_matrix



if(TRUE) message("it was true")
if(FALSE) messgae("it wasn't true")

x<-3
if(x>2){
  y<-2*x
  z<-3*y
}
y
z

if(FALSE) {
  message("this won't be execute")
  }else{
  message("but this will")
  }


yn<-rep.int(c(TRUE,FALSE),6)
yn
ifelse(yn,1:3,-1:-12)



if(c(0)) message("hello")


greek<-switch("gama",
              alpha=1,
              beta=sqrt(4),
              gama={
                a<-sin(pi/3)
                4*a^2
              })
greek

greek<-switch("gama",
              alpha=1,
              beta=sqrt(4),
              gama2={
                a<-sin(pi/3)
                4*a^2
              })
greek




repeat{
  message("Happy groundhog day!")
  action<-sample(c(
    "learn French",
    "make an ice statue",
    "ROb a bank",
    "win heart of Andie Mcdowell"
  ),1)
  message("action=",action)
  if(action == "win heart of Andie Mcdowell")
    break
}






for (i in 1:5) message("i=",i)

for(i in 1:5){
  j<-i^2
  message("j=",j)
}


for(month in month.name){
  message(month)
}
for(yn in c(TRUE,FALSE,NA)){
  message("This statement is ", yn)
}
l<-list(pi,LETTERS[1:5],charToRaw("not as complicated as it
 looks"))
for(i in l){
  print(i)
}



an_env<-new.env()
an_env

an_env[["pythag"]] <- c(12,15,20,21)
an_env$pythag
an_env$root <- polyroot(c(6,-5,1))
an_env$root

?polyroot


assign("monday",weekdays(as.Date("1969-07-20")),an_env)
an_env[["pythag"]]
an_env$root
get("monday",an_env)


nested_env<-new.env(parent=an_env)
exists("pythag",nested_env)
exists("pythag",nested_env,inherits=FALSE)

non_stormers<<-c(3,7,8,13,17,18,21)
get("non_stormers",envir=globalenv())


twosam <- function(y1,y2){
  n1 <- length(y1); n2<- length(y2)
  yb1 <- mean(y1); yb2 <- mean(y2)
  s1 <- var(y1); s2<- var(y2)
  s <- ((n1-1)*s1 + (n2-1)*s2)/(n1+n2-2)
  tst <- (yb1 - yb2)/sqrt(s*(1/n1 + 1/n2))
  print(yb1)
  print(yb2)
  print(s1)
  print(s2)
  print(s)
  print(tst)
}

twosam(c(1:3),c(4:6))