Great, that works very well. What is the purpose of double brackets vs single ones? I will remember next time to include a subset of the data, so that readers can run the script. Thanks again for your help!
Benilton Carvalho wrote: > > it appears that what you really want is to use: > > task[[i]] > > instead of task[i] > > b > > On Nov 1, 2009, at 11:04 PM, dadrivr wrote: > >> >> I would like to preface this by saying that I am new to R, so I >> would ask >> that you be patient and thorough, so that I'm not completely >> clueless. I am >> trying to convert a list to numeric so that I can perform >> computations on it >> (specifically mean-center the variable), but I am running into >> problems. I >> have imported the data set into "task" (data frame). The data frame >> is made >> of factors with variable names in the first row. I am running a >> loop to set >> a variable equal to a column in the data frame. Here is an example >> of my >> problem: >> >> for (i in 1:dim(task)[2]){ >> predictor.loop <- c(task[i]) >> predictor.loop.mc <- predictor.loop - mean(predictor.loop, na.rm=T) >> } >> >> I get the following error: >> Error in predictor.loop - mean(predictor.loop, na.rm = T) : >> non-numeric argument to binary operator >> In addition: Warning message: >> In mean.default(predictor.loop, na.rm = T) : >> argument is not numeric or logical: returning NA >> >> The column is entirely made up of numerical data, except for the >> header, >> which is a string. My problem is that I receive an error because the >> predictor.loop variable is not numerical, so I need to find a way to >> convert >> it. I tried using: >> predictor.loop <- c(as.numeric(task[i])) >> But I get the following error: "Error: (list) object cannot be >> coerced to >> type 'double'" >> >> If I call the variable, I can assign it to a numerical list (e.g., >> predictor >> loop <- task$variablename), but since I am assigning the variable in >> a loop, >> I have to find another way as the variable name would have to change >> in each >> loop iteration. Any help would be greatly appreciated. Thanks! >> -- >> View this message in context: >> http://old.nabble.com/convert-list-to-numeric-tp26155039p26155039.html >> Sent from the R help mailing list archive at Nabble.com. >> >> ______________________________________________ >> 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. > > ______________________________________________ > 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. > > -- View this message in context: http://old.nabble.com/convert-list-to-numeric-tp26155039p26157105.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ 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.