Homework Problem 1 Solution.

###(a)-(f) 
> W1 = c(rep(c(5,8,2),40), rep(c(1,4,2,0),30))
  W2 = ifelse(rep(c(T,F),120), cos((1:240)/7), 
                 1/sqrt(1+0.3*(1:240)^2))
  W3 = (W1 == 4 | W1==8)
  W4 = ifelse(!W3, "A", ifelse(W2< 0.17, "B", "C")) 
  MM = matrix(c(W1,W2,W3,W4), nrow=240, dimnames=list(
          NULL, c("Seq", "Num", "TVal", "Class")))
  MMalt = cbind(Seq=W1, Num=W2, TVal=W3, Class=W4)
  Dfr = cbind.data.frame(Seq=W1, Num=W2, TVal=W3, Class=W4)
> class(MM)
[1] "matrix"
> c(class(MM[,2]),class(MM[,2])) 
[1] "character" "character"


## final part (g)
  Dfr[c(1,4,6,10,11,20,30,100,119),]
    Seq           Num  TVal Class
1     5  0.9898132604 FALSE     A
4     5  0.4152273993 FALSE     A
6     2  0.2911112549 FALSE     A
10    5  0.1796053020 FALSE     A
11    8 -0.0006322446  TRUE     B
20    8  0.0909090909  TRUE     B
30    2  0.0607456739 FALSE     A
100   5  0.0182543764 FALSE     A
119   8 -0.2751633381  TRUE     B