【R】语言第三课----矩阵

【R】语言第三课----矩阵

#矩阵?matrixm<-matrix(1:6,nrow = 2,ncol=3, dimnames = list(c('r1','r2'),c('c1','c2','c3')))m#默认按列排列m<-matrix(1:6,nrow = 2,ncol=3,byrow = T, dimnames = list(c('r1','r2'),c('c1','c2','c3')))mclass(m)m[1,1] m[1,]# 相当于 m[c(T,F),]m[,1]m['r1',]m[1,] <- c(100,99,98)mm[1,] <- 100mt(m)#数组 维度可以大于2?arrayarray(1:10)array(1:10,dim = c(2,5))array(1:12,c(2,3,2))dim1<-c('A1','A2')dim2<-c('B1','B2','B3')dim3<-c('C1','C2')arr3<-array(1:12,c(2,3,2),dimnames = list(dim1,dim2,dim3))arr3[,,'C1']arr3[,,1]arr3[,,c(T,F)]#数据框data.frame()student<-data.frame(ID=c(1001,1002,1003), NAME=c('lili','bob','sam'), GENDER=c('F','M','M'))studentstudent<-data.frame(ID=c(1001,1002,1003), NAME=c('lili','bob','sam'), GENDER=c('F','M','M'),stringsAsFactors = F)studentstudent[1,1]<-1009student[1,]student[,1]student[,'ID'] #向量student['ID'] #数据框student$IDstudent[c('ID','NAME')]student#列表list()list1<-list(a=1,b='char',c=m,d=student)list1list1[[1]]list1[['a']]list1[[4]]list1[['d']]list1[4]class(list1[4])#homework Q1A<-matrix(1:12,nrow=3)AB<-matrix(1:12,ncol=4,byrow = T)B#homework Q2B[,1]<-100B#homework Q3wtdata<-data.frame(ID=c(1,2,3), name=c('张三','李四','王五'),stringsAsFactors = F, weight=c(60,70,80))wtdatastr(wtdata)#homework Q4wtdata[c(1,3),]#homework Q5wtlist<-list(a='A',b='B',c=wtdata)wtlist#homework Q6wtlist[[1]]

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