[R] (no subject)

[(Ted Harding)]

On 12-Mar-04 Padmanabhan, Sudharsha wrote:
> I have an array c as follows
> 
> 1     23      12
> 1     34      15                      
> 1     45      67
> 1     45      87
> 2     78      23
> 2     65      19
> 2     45      90
> 2     70      32
> 
> 
> Col 1 indicates treatment, col2 is the observed readings and col3 
> is some summary statistic I have calculated after breaking the ties
> in col 2 arbitrarily.
> 
> Now I want to average the statistics of the tied values. So, in col 3
> for each of the reading of 45 , I now want (67+87+90)/3 = 81.33
> 
> 
> 1     23      12
> 1     34      15                      
> 1     45      81.33
> 1     45      81.33
> 2     78      23
> 2     65      19
> 2     45      81.33
> 2     70      32

tmp<-matrix(c(
1,23,12,
1,34,15,
1,45,67,
1,45,87,
2,78,23,
2,65,19,
2,45,90,
2,70,32),ncol=3,byrow=TRUE)

for( i in (unique(tmp[,2])) ){
     m <- mean(tmp[tmp[,2]==i,3]);
     tmp[tmp[,2]==i,3] <- m
}

tmp
     [,1] [,2]     [,3]
[1,]    1   23 12.00000
[2,]    1   34 15.00000
[3,]    1   45 81.33333
[4,]    1   45 81.33333
[5,]    2   78 23.00000
[6,]    2   65 19.00000
[7,]    2   45 81.33333
[8,]    2   70 32.00000

(You could make the assignment within the for-loop even more
 concise but the above shows explicitly what is going on).

Hope this helps!
Ted.


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E-Mail: (Ted Harding) <Ted.Harding at nessie.mcc.ac.uk>
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Date: 12-Mar-04                                       Time: 22:52:24
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