Thanks Mark! Mark Leeds wrote: > Hi Ricardo: you can look at ?regexpr but I'm pretty sure that below returns > a vector of TRUES and FALSES depending on whether the condition ( is Jalapa > contained in unidad ) is TRUE. So, wherever the vector is TRUE is where > Jalapa was contained in unidad. So, it's basically EXACTLY the same > as what Henrique did. I just can't remember exactly what Henrique did > at the moment. > > regexpr("Jalapa", as.character( unidad ) ) != -1 > > So, suppose your dataframe was called DF and it has column called unidad. > > Then, > > newDF<-DF[(regexpr("Jalapa", as.character( unidad ) ) != -1),] > > should be a new dataframe , exactly the same as the old one, but only > containing the rows where the condition was true. Does that clear things up > for you ?
Yes. It is clear for me now. Thanks for your detailed explanation! > The expression is for the rows and has the TRUES and FALSES as a > vector and whenever it is TRUE, the row is kept and whatever is FALSE, the > row is not kept. The comma just says to take all the columns. > > You can also use subset directly if that's easier for you the same way > you figured out how to use it in the state.77 example. > > If it's not clear, it's because you need to understand how logical > subscripting is used in R. For that, I think the thing to read is > "Introduction to R" which is one of the documents at www.r-project.org. > > Do > > Yes, this is the main problem: I need to understand basic concepts. And I am aware that logical subscripting is not one of my strengths. The example has also forced me to understand another basic concetp: attach() and detach()! I didn't know why unidad was not available just by name in my environment. I used to call variables as name$dataframe. > temp<- regexpr("Jalapa", as.character( unidad ) ) != -1 > print(temp) > > to see exactly what regexpr does. Thanks again. Cheers, Ricardo -- Ricardo RodrÃguez Your XEN ICT Team ______________________________________________ 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.