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 [email protected] [[alternative HTML version deleted]] _______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-sig-teaching
-- ##################################### 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/ _______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-sig-teaching
