[R] simple problem, but not for me

[alexbri]

Hello, I'm new in R and I want to do one thing that is very easy in excel, however, I cant do it in R.

Suppose we have the data frame:

 

data<- data.frame(A=c("a1","a2","a3","a4","a5"))

 

I need to obtain another column in the same data frame (lets say B=c(b1,b2,b3,b4,b5) in the following way:

 

b1=a1/(a1+a2+a3+a4+a5)

b2=a2/(a2+a3+a4+a5)

b3=a3/(a3+a4+a5)

b4=a4/(a4+a5)

b5=a5/a5

 

a1..a5 and b1...b5 are always numeric values

 

(this is just an example, what I really want is apply this kind of formula to a much larger data frame)

 

I think this is easy for those who are used to work in R (and I suppose there are many different ways), but I can make it in this moment, because I cannot leave behind, the "excel thinking way".

I hope you understand my problem and please, help me soon. 

 

Alexandre

 

alexbri at netcabo.pt