[R-sig-teaching] Calculation with R
Jeff Laux
jefflaux at gmail.com
Fri Jul 22 15:19:49 CEST 2016
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]]
> >>
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