On Fri, 10 Mar 2006, Matthew Scholz wrote: > Thanks for your response, Christos, but when I try this: > >> new = old[old$q.D1 < 0.05,] > > I get the following warning (and what I'm trying to do fails): > > Warning message: > < not meaningful for factors in: Ops.factor(old$q.D1, 0.05) > > I've tried to bone up on the topic of factors and searching R help, > but I'm still not sure why my data is being converted to that class > nor do I know how to undo the conversion or work around it. Thanks > again in advance of your advice. Any suggestions?
How to undo the conversion is FAQ 7.10 -thomas > > Matt > > On 3/9/06, Christos Hatzis <[EMAIL PROTECTED]> wrote: >> You can try: >> >> new.dataframe <- my.dataframe[my.dataframe$p.value < 0.05, ] >> >> This will select all columns. Alternatively, you can specify the columns >> that you want after the ",". >> >> -Christos >> >> -----Original Message----- >> From: [EMAIL PROTECTED] >> [mailto:[EMAIL PROTECTED] On Behalf Of Matthew Scholz >> Sent: Thursday, March 09, 2006 5:18 PM >> To: r-help@stat.math.ethz.ch >> Subject: [R] newbie question: grouping rows >> >> Hi all, >> >> I have a very simple question that I can't seem to find the answer to. >> How do I extract rows that meet a certain criteria from a data frame and >> group them into a new data frame? For example, if I want to make a new data >> frame that only includes rows of data for which the p values (given by one >> of the columns in the data frame) are less than a certain value, how do I do >> this? It seems that there should be a simple function that does this. I >> looked into getGroups from the nmle package, but am not sure how to >> construct the form argument correctly or even if it's the appropriate way to >> tackle this. >> >> Thanks in advance of your answer, >> >> Matt >> >> ______________________________________________ >> R-help@stat.math.ethz.ch mailing list >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide! >> http://www.R-project.org/posting-guide.html >> >> >> > > ______________________________________________ > R-help@stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html > Thomas Lumley Assoc. Professor, Biostatistics [EMAIL PROTECTED] University of Washington, Seattle ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html