Dear Bill, thank you for your help. I think, I finally understood your advice. At least, this one worked:
library(package = lubridate) # for a more convenient display of times i <- 12 # number of time intervals per hour # creating a data.frame (original example) business_hours <- data.frame(t = hm(paste(rep(x = 0:23, each = i), rep(x = seq(from = 0, to = 60/i * (i - 1), by = 60/i), times = 24))), A = c(rep(x = 0, times = (8 - (1/i)) * i), 1, rep(x = 0, times = (12 - (1/i)) * i), -1, rep(x = 0, times = (4 ) * i)), B = c(rep(x = 0, times = (9 - (1/i)) * i), 1, rep(x = 0, times = (2.75 - (1/i)) * i), -1, rep(x = 0, times = (1.75 - (1/i)) * i), 1, rep(x = 0, times = (3.5 - (1/i)) * i), -1, rep(x = 0, times = 7 * i))) # some data analysis plot(x = rowSums(x = cumsum(business_hours[, -1])), type = "s") I find some elegance in this solution; still, Jims proposal looks easier to handle to me. Best regards, Alex -- Alexander Sommer wissenschaftlicher Mitarbeiter Technische Universität Dortmund Fakultät Erziehungswissenschaft, Psychologie und Soziologie Forschungsverbund Deutsches Jugendinstitut/Technische Universität Dortmund Vogelpothsweg 78 44227 Dortmund Telefon: +49 231 755-8189 Telefax: +49 231 755-6553 E-Mail: alexander.som...@tu-dortmund.de WWW: http://www.forschungsverbund.tu-dortmund.de/ Wichtiger Hinweis: Die Information in dieser E-Mail ist vertraulich. Sie ist ausschließlich für den Adressaten bestimmt. Sollten Sie nicht der für diese E-Mail bestimmte Adressat sein, unterrichten Sie bitte den Absender und vernichten Sie diese Mail. Vielen Dank. Unbeschadet der Korrespondenz per E-Mail, sind unsere Erklärungen ausschließlich final rechtsverbindlich, wenn sie in herkömmlicher Schriftform (mit eigenhändiger Unterschrift) oder durch Übermittlung eines solchen Schriftstücks per Telefax erfolgen. Important note: The information included in this e-mail is confidential. It is solely intended for the recipient. If you are not the intended recipient of this e-mail please contact the sender and delete this message. Thank you. Without prejudice of e-mail correspondence, our statements are only legally binding when they are made in the conventional written form (with personal signature) or when such documents are sent by fax. ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.