My last query related to this referred to a problem with not being able to store data. A suggestion was made to try to convert the data returned by fitdist into a data.frame before using rbind. That failed, but provided the key to solving the problem (which was to create a data.frame using the variables fitdist produces in the object it returns).
I now have almost everything working as intended. However, there is one problem. Here is the error: 'data.frame': 0 obs. of 0 variables Error in `[.data.frame`(moreinfo, , 1) : undefined columns selected Calls: [ -> [.data.frame Execution halted the curious thing is that this happens when my script is called from within perl. Within Rgui, the script continues through to the end, but the loop that is involved terminates at the line where this error occurs. The line that results in this error is: moreinfo <- dbGetQuery(con, x) This statement occurs in a loop that ought to iterate over a few hundred values for m_id (see the SQL below). Because of the above error, I never see about two thirds of the results that ought to be produced. At the time that the error occurs, x contains the following SQL query: SELECT m_id,sale_date,YEAR(sale_date) AS sale_year,MONTH(sale_date) AS sale_month,return_type,0.0001 + DATEDIFF(return_date,sale_date) AS elapsed_time FROM `merchants2`.`risk_input` WHERE m_id = 361 AND return_type = 1 AND DATEDIFF(return_date,sale_date) IS NOT NULL; If I execute this SQL, I find the resultset is empty. So assigning the value returned by dbGetQuery to moreinfo works ONLY if the resultset is not empty. It fails with a fatal error if the resultset is empty. So, the question is, how can I revise that statement so that the assignment happens only if the resultset is NOT empty? 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.