Try the following commands
>mydata<-c(2.9, 3.4, 3.4, 3.7, 3.7, 2.8, 2.8, 2.5, 2.4, 2.4);
>colors<-c("red", "green", "blue", "white", "black");
>x1<-25:30;
>x1
>mydata[7]
>colors[3]
>mydata>3
>names(mydata)
>names(mydata) <-c('c', 'j', 'b', 'e', 'i', 'h', 'g', 'd', 'f', 'a');
>mydata
>names(mydata)
>mydata['e']
>letters[1:5] ##letters is a pre-defined R vector of the 26 lowercase letters
>mydata[letters[1:5]]
>mydata[mydata >3]
>mydata[-c(3:5)]
>mode(mydata)
>mode(letters)
>length(mydata)
>length(letters)
>dim(mydata)
>dim(mydata) <- c(2,5);
>mydata
>dim(mydata) <- NULL;
>mydata
>a <- c(1,3,6);
>a[a>2];
>b<-c("red", "blue", "green", "black");
>b[-c(1,3)];
>cc<-c(TRUE, FALSE, FALSE, FALSE);
>x<-list(a,b,cc);
>x[[1]][2]
2. Elementary matrix operations
>A<-matrix(c(1,2,4,7,5,9),2,3, byrow=T);
>dim(A)
>nrow(A)
>ncol(A)
>t(A)
>B<-matrix(rep(1,6),3,2);
>C<-matrix(rep(2,6),2,3);
>A * B
>A %*% B
>A * C
>A %*% C
>rbind(A,B)
>rbind(A,C)
>cbind(A,B)
>cbind(A,C)
>D<-matrix(c(1,0,1,0),2,2);
>E<-matrix(c(1,0,0,1),2,2);
>F<-matrix(0,2,2);
>diag(F)<-c(1,1);