不同数据类型

getwd()
#R语言复习
#向量
a<-c(1:10)  
a
class(a)  #a的数据类型
is.numeric(a) #判断a是否是数值型
a[2]  #读取第二个数值
a[2:5]
a[c(1,2,5)]


#矩阵
?matrix() #
b<-c(1:15)
b
newmatrix<-matrix(b,nrow = 3,ncol = 5,byrow = FALSE,dimnames = list(c("第一行","第二行","第三行"),c(1:5)))
newmatrix[3,2]
newmatrix[,4]


#数组
?array
dim1<-c("x1","x2")
dim2<-c("y1","y2","y3")
dim3<-c("z1","z2","z3","z4")
newarray<-array(c(2:25),c(3,4,2),dimnames = list(dim2,dim3,dim1))
newarray
newarray[1,2,2]
newarray[1,2,]

#数据框
?data.frame
ID<-c(14,21,23,45)
age<-c(25,24,52,32)
hypertension<-c("yes","no","yes",NA)
patientdata<-data.frame(ID,age,hypertension)
patientdata