[R-sig-teaching] Calculation with R

[Jeff Laux]

I have to agree here.  This question (and more generally most of the 
questions I've seen you post) do not belong on this particular list.  
There are a number of appropriate places where you should be able to get 
help with this.  Moreover, this question is really trivial, and 
shouldn't be a problem once you've been using R for a week or two.


On 7/22/2016 3:13 AM, Martin Maechler wrote:
>>>>>> Randall Pruim <rpruim at calvin.edu>
>>>>>>      on Thu, 21 Jul 2016 15:32:00 +0000 writes:
>      > This isn’t really a teaching question,
>
> Yes, indeed this is NOT  about 'teaching R'  or
> 'teaching with R', and hence not appropriate for the
> R-SIG-teaching list.
>
> Please, Steven Stoline, stop misusing this list for your questions about R.
>
> There is the R-help mailing list for that, and other fora,
> such as Stackoverflow, see
>
> https://www.r-project.org/posting-guide.html    and also
> https://www.r-project.org/mail.html
>
> Martin Maechler
> (ETH Zurich / R Core)
>
>      > but for your particular case IIYC, just multiply the squared quantity by data[,2] before summing.  For more general cases, take a look at ifelse().
>      >> On Jul 21, 2016, at 11:20 AM, Steven Stoline <sstoline at gmail.com> 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
>
>      > _______________________________________________
>      > R-sig-teaching at r-project.org mailing list
>      > https://stat.ethz.ch/mailman/listinfo/r-sig-teaching
>
> _______________________________________________
> R-sig-teaching at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-sig-teaching