[R-sig-teaching] Calculation with R

[Tim Appelhans]

Steve,

sum((data[ ,1][data[, 2] == 1] - a)^2)

Hope that helps,
Tim

On 21.07.2016 17:20, Steven Stoline wrote:
> Dear All: good morning
>
> I do need your help how to do the following calculation:
>
> Assume we have a matrix 13x2 (say). Two columns named dataval and index
>
> dataval index
> 20 1
> 11 0
> 34 0
> 54 1
> 76 1
> 76 0
> 61 1
> 88 1
> 91 0
> 11 0
> 23 1
> 45 1
> 53 0
>
> data<-matrix(c(20,11,34,54,76,76,61,88,91,11,23,45,53,1,0,0,1,1,0,1,1,0,0,1,1,0),13,2)
>
> data
>
> I need to perform the calculation:
>
> for a = 7 (say)
>
> sum((data[ ,1] - a)^2)
>
> only for index = data[ ,2] = 1
>
>
> I am expecting the result to be equal to:
>
> (20-7)^2 + (54-7)^2+(76-7)^2+(61-7)^2+(88-7)^2+(23-7)^2+(45-7)^2 = 18316
>
>
> Any helps will be highly appreciated.
>
>
> with many thanks
> steve
> -------------------------
> Steven M. Stoline
> 1123 Forest Avenue
> Portland, ME 04112
> sstoline at gmail.com
>
> 	[[alternative HTML version deleted]]
>
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-- 
#####################################
Tim Appelhans
Department of Geography
Environmental Informatics
Philipps Universität Marburg
Deutschhausstraße 12
Raum 00A08
35032 Marburg (Paketpost: 35037 Marburg)
Germany

Tel +49 (0) 6421 28-25957

http://environmentalinformatics-marburg.de/