dear all, thank you for reading.
I have a dataset of artists and where and when they had an exhibition. I'd like to create an affiliation network in the form of matrix, telling me which aritist have been in the same at the same time. I manage to do it, but given that I have 96000 observation the program takes 30 months to complete. her what i have done. the data look like this Artist <-c(1,2,3,2,4,4,5) Begin <- as.Date(c('2006-08-23', '2006-03-21', '2006-03-06', '2006-01-13', '2006-05-20', '2006-07-13', '2006-07-20')) End <- as.Date(c('2006-10-23', '2006-11-30', '2006-05-06', '2006-12-13', '2006-09-20', '2006-08-13', '2006-09-20')) Istitution <- c(1, 2, 2, 1, 1, 2, 1) artist is the name of the artist, Begin and End is the when and Istitutionis the where. my IF is working, #number of unique artist c <- unique(Artist) d <- length(c) a <-length(Artist) B <- mat.or.vec(d,d) for(i in 1:d) { for(j in 1:d) { if (Istitution[i] == Istitution[j]) { if (Begin[i] <= End[j]) { if (End[i]-Begin[j] >= 0) { B[i,j] <- B[i,j]+1 B[i,i] <- 0 } } else{ if (End[j]-Begin[i] >= 0) { B[i,j] <- B[i,j]+1 B[i,i] <- 0 } } } } print(i) } do you have a way to make the programm simpler and faster? thank you very much Marco Guerzoni, Department of Economics University of Turin -- View this message in context: http://r.789695.n4.nabble.com/If-cycle-takes-to-much-time-tp4656601.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.