[R] how to do this "the R way"

onyourmark william108 at gmail.com
Sat Apr 4 05:36:10 CEST 2009


Hi. 
 newTS2 =(perm[100.TS2[1]]. perm[100.TS2[2]]. perm[100.TS2[3]]. ... ,
perm[100.TS2[2000]])

newTS2 is supposed to be a vector of 2000 values.
The first value is supposed come from a particular element of the matrix
called 'perm'.

I thought that 
perm[100.TS2[1]]
would be valid code in R to refer to that element.
It is meant to choose the element from 'perm' in the 100th row and in the
column indicated by
TS2[1]. In other words, TS2[1] is the first element in the TS2 vector. 

For example, if the first element in the TS2 vector was 5 then I would want
to choose the (100,5) element from perm to be the first entry in 
newTS2.

Does this make sense? Thanks.

onyourmark wrote:
> Hi. I am sure there is a better way in R to do this then using a loop but
> I
> am new to it and not sure what to do. I think it might be something about
> using a function as an argument but not sure.
> 
> I have a 1 x 2000 vector TS2 which has entries from the set {x: x is in Z
> and 0<x<8} (where Z is the set of Integers).
> 
> Then I also have a 5050 x 7 matrix called 'perm' whose entries are also
> from
> the set {x: x is in Z and 0<x<8}
> 
> I want to construct the following transformation of TS2 which will still
> be
> a vector of size 1 x 2000 and which I will call 'newTS2' such that:
> 
> newTS2 =(perm[100.TS2[1]]. perm[100.TS2[2]]. perm[100.TS2[3]]. ... ,

Perhaps you can explain what the last line is supposed to do? This is 
invalid R code and also not a known mathematical notation for me ....

Uwe Ligges


> perm[100.TS2[2000]])
> 
> Is there a nice way to do this without a loop?
> 
> Thank  you.

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