Hello R users, The code below is for loop in R that I want to do to following calculation at each time i and i-1 in 2:75 dataset (Litterfall_Ahmed97).
ac = ((LeafBiog at date i -LeafBiog at date i-1, dataset = leafbiom97) + (littperiod at date i, dataset= Litterfall_Ahmed97))/(sum (GPP from date i-1 to date i, dataset=GPP_Ahmed13)/2) . #code for loop GPP_Ahmed13$Date <- as.Date(GPP_Ahmed13$Date, '%Y/%m/%d') Litterfall_Ahmed97$Date <- as.Date(Litterfall_Ahmed97$Date, '%Y/%m/%d') leafbiom97$Date <- as.Date( leafbiom97$Date, '%Y/%m/%d') for (i in 2:75){ (leafbiom97$LeafBiog[leafbiom97$Date == "i"] - leafbiom97$LeafBiog[leafbiom97$Date == "i-1"]+ Litterfall_Ahmed97$littperiod[Litterfall_Ahmed97$Date =="i"])/ (sum(GPP_Ahmed13$GPP[GPP_Ahmed13$Date >= "i-1" & GPP_Ahmed13$Date <= "i"])/2) } #Error in charToDate(x) : Thanks for your help Ahmed Attia, Ph.D. Agronomist & Soil Scientist ______________________________________________ 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.