[R] simple problem, but not for me

[Uwe Ligges]

alexbri wrote:

> 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


   temp <- rev(data$A)
   data$B <- rev(temp / cumsum(temp))

Uwe Ligges




>  
> 
> 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
> 
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