[R-sig-teaching] Calculation with R

[Gabor Grothendieck]

Might be clearer if some variables are created first::

values <- data[, 1]
ok <- data[, 2] == 1
sum( (values[ok] - 7)^2 )

On the other hand if you prefer obsfucation replace the last line with:

deviance(lm(values-7 ~ 0, subset = ok))


On Thu, Jul 21, 2016 at 11:27 AM, Tim Appelhans <tim.appelhans at gmail.com> wrote:
> 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]]
>>
>> _______________________________________________
>> R-sig-teaching at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-sig-teaching
>
>
> --
> #####################################
> Tim Appelhans
> Department of Geography
> Environmental Informatics
> Philipps Universität Marburg
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> Germany
>
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>
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>
>
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