I wasn't even aware I was using midnightStandard. You won't find it in my script.
Here is the relevant loop: date1 = timeDate(charvec = Sys.Date(), format = "%Y-%m-%d") date1 dow = 3; for (i in 1:length(V4) ) { x = read.csv(as.character(V4[[i]]), header = FALSE, na.strings=""); y = x[,1]; year = V2[[i]]; week = V3[[i]]; dtstr = sprintf("%i-%i-%i",year,week,dow); date2 = timeDate(dtstr, format = "%Y-%U-%w"); resultsdataframe$dt[[i]] <- difftimeDate(date1,date2,units = "weeks"); fp = fitdistr(y,"exponential"); print(c(V1[[i]],V2[[i]],V3[[i]],fp$estimate,fp$sd)); print(c(year,week,date2,resultsdataframe$dt[[i]])); resultsdataframe$estimate[[i]] <- fp$estimate; resultsdataframe$sd[[i]] <- fp$sd; } It fails with a little more than 100 records left in V4. The full error message is: Error in midnightStandard(charvec, format) : 'charvec' has non-NA entries of different number of characters Until it fails, date2 and resultsdataframe$dt[[i]] get correct values. str() produces no surprises: > str(resultsdataframe); 'data.frame': 303 obs. of 6 variables: $ mid : int 171 206 206 206 206 206 206 206 206 218 ... $ year : int 2008 2008 2008 2008 2008 2008 2008 2008 2008 2008 ... $ week : int 16 17 18 19 21 26 31 35 51 40 ... $ dt : num 39.9 38.9 37.9 36.9 34.9 ... $ estimate: num Inf 0.25 Inf 0.0408 0.2 ... $ sd : num Inf 0.1768 Inf 0.0289 0.1414 ... I would assume the error is related to my new code that manipulates dates, as it doesn't occur in the earlier version that did not manipulate dates (the relevant work being done, albeit very slowly, within the DB). FTR: The year and week values are generated by MySQL using the YEAR and WEEK functions applied to timestamps. I do not know if it is relevant, but the week value, at the point of failure, is 0 (a value that does not occur earlier in the dataset, but several times subsequently), and I do not see how a value of 0 for the week (legitimate in posix date formats) could produce the error message I get. Any thoughts on what is really wrong, and how to fix it? Thanks Ted [[alternative HTML version deleted]] ______________________________________________ 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.