[R] alternate methods to perform a calculation
jim holtman
jholtman at gmail.com
Wed Aug 29 01:49:43 CEST 2007
I think you can use 'outer'
outer(b$xk1, a$x1, function(y,z)abs(z-y))
outer(b$xk2, a$x2, function(y,z)abs(z-y))
On 8/28/07, dxc13 <dxc13 at health.state.ny.us> wrote:
>
> Consider a data frame (x) with 2 variables, x1 and x2, having equal values.
> It looks like:
>
> x1 x2
> 1 1
> 2 2
> 3 3
>
> Now, consider a second data frame (xk):
> xk1 xk2
> 0.5 0.5
> 1.0 0.5
> 1.5 0.5
> 2.0 0.5
> 0.5 1
> 1.0 1
> 1.5 1
> 2.0 1
> 0.5 1.5
> 1.0 1.5
> 1.5 1.5
> 2.0 1.5
> 0.5 2
> 1.0 2
> 1.5 2
> 2.0 2
>
> I have written code to calculate some differences between these two data
> sets; the main idea is to subtract off each element of xk1 from each value
> of x1, and similarly for xk2 and x2. This is what I have:
>
> w1 <- array(NA,dim=c(nrow(xk),length(x$x1)))
> w2 <- array(NA,dim=c(nrow(xk),length(x$x2)))
> for (j in 1:nrow(xk)) {
> w1[j,] <- abs(x$x1-xk$xk1[j])
> w2[j,] <- abs(x$x2-xk$xk2[j])
> }
>
> Is there a way to do the above calculation without use of a FOR loop?
> Thank you
>
> Derek
>
>
> --
> View this message in context: http://www.nabble.com/alternate-methods-to-perform-a-calculation-tf4344469.html#a12376906
> Sent from the R help mailing list archive at Nabble.com.
>
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--
Jim Holtman
Cincinnati, OH
+1 513 646 9390
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