Dividing variables by other variables within a dataframe

Question

I have a dataframe with several variables listed by year. I want to divide a set of variables by other variables of the same year. So for example:

Dataframe:

Variable: A B C D AA BB CC DD

I want to create new columns of A/AA B/BB C/CC D/DD etc..

I have tried creating a function:

i<- 1:4
ii<-5:8
A<- function(x){i/ii}

Then running the apply function:

apply(dataframe[1:8], 2, A)

But this is not correct. Please help!

Answer 1

Is this what you're looking for?

a<-as.data.frame(matrix(80:1,ncol=8))
a
   V1 V2 V3 V4 V5 V6 V7 V8
1  80 70 60 50 40 30 20 10
2  79 69 59 49 39 29 19  9
3  78 68 58 48 38 28 18  8
4  77 67 57 47 37 27 17  7
5  76 66 56 46 36 26 16  6
6  75 65 55 45 35 25 15  5
7  74 64 54 44 34 24 14  4
8  73 63 53 43 33 23 13  3
9  72 62 52 42 32 22 12  2
10 71 61 51 41 31 21 11  1

a[1:4]/a[5:8]
         V1       V2       V3        V4
1  2.000000 2.333333 3.000000  5.000000
2  2.025641 2.379310 3.105263  5.444444
3  2.052632 2.428571 3.222222  6.000000
4  2.081081 2.481481 3.352941  6.714286
5  2.111111 2.538462 3.500000  7.666667
6  2.142857 2.600000 3.666667  9.000000
7  2.176471 2.666667 3.857143 11.000000
8  2.212121 2.739130 4.076923 14.333333
9  2.250000 2.818182 4.333333 21.000000
10 2.290323 2.904762 4.636364 41.000000