Re: [R] summation coding

2012-10-19 Thread cberry
djbanana writes: > Hi, > > I think I solved it myself by writing loops. > > What I meant is: are there in-built functions in R that calculate the > following: > > a1(b2+...+b190) + a2(b1+b3+...+b190) + ... Following Rainer's setup: x <- data.frame( a = sample( 1:10, 4 ), b = sample( 11:20, 4 )

Re: [R] summation coding

2012-10-19 Thread djbanana
Hi, I think I solved it myself by writing loops. What I meant is: are there in-built functions in R that calculate the following: a1(b2+...+b190) + a2(b1+b3+...+b190) + ... I managed to solve it, quite similar to what you just emailed. Thanks anyway! -- View this message in context: http:

Re: [R] summation coding

2012-10-19 Thread Berend Hasselman
On 19-10-2012, at 10:38, Berend Hasselman wrote: > > On 18-10-2012, at 21:33, djbanana wrote: > >> I would like to code the following in R: a1(b1+b2+b3) + a2(b1+b3+b4) + >> a3(b1+b2+b4) + a4(b1+b2+b3) >> >> or in summation notation: sum_{i=1, j\neq i}^{4} a_i * b_i >> >> I realise this is the

Re: [R] summation coding

2012-10-19 Thread Berend Hasselman
On 18-10-2012, at 21:33, djbanana wrote: > I would like to code the following in R: a1(b1+b2+b3) + a2(b1+b3+b4) + > a3(b1+b2+b4) + a4(b1+b2+b3) > > or in summation notation: sum_{i=1, j\neq i}^{4} a_i * b_i > > I realise this is the same as: sum_{i=1, j=1}^{4} a_i * b_i - sum_{i=j} a_i > * b_i

Re: [R] summation coding

2012-10-19 Thread Rainer Schuermann
You asked for a loop, you got one... Vectorized is easier and faster: x$c <- x$a * ( sum( x$b ) - x$b ) Rgds, Rainer On Friday 19 October 2012 09:38:35 you wrote: > Hi, > > I think I solved it myself by writing loops. > > What I meant is: are there in-built functions in R that calculate the

Re: [R] summation coding

2012-10-19 Thread Rainer Schuermann
Assuming that you actually mean a1(b2+b3+b4) + a2(b1+b3+b4) + a3(b1+b2+b4) + a4(b1+b2+b3) ^ ^ ^ this might give you what you want: x <- data.frame( a = sample( 1:10, 4 ), b = sample( 11:20, 4 ) ) x

Re: [R] summation coding

2012-10-18 Thread djbanana
I am aware of the most basic stuff, especially vectorization and subscripting. I only gave a simple example with length 4. I need to do that for vectors of length 190. Are there any in-built commands? Or should I write the loops myself? Thank you. -- View this message in context: http://r.7

Re: [R] summation coding

2012-10-18 Thread Bert Gunter
Have you read the Introduction to R tutorial? You seem unaware of even the most basic stuff, especially vectorization and subscripting. Also, this smells like homework, and we don't do homework here. -- Bert On Thu, Oct 18, 2012 at 12:33 PM, djbanana wrote: > I would like to code the following