Thank you very much, looks rather simple when viewed from behind :(
> Try this also: > xtabs(values ~ diagnosis + marker, data=dataframe) > You can make your examples self-running by providing fake data for > diagnosis, e.g. using letters[] instead of diagnosis. In addition, note that > your cbind has an awkward side effect by converting everything to character > as the least common denominator for the variables in a matrix. > For real work, use reshape with its frightening number of parameters. If you > don't understand that function at the seventh reading, stay cool: it's not > your fault. You might also try package reshape, but it is not much easier > for occasional use. > Dieter > diagnosis <- as.factor(rep(letters[1:3], 3)) > marker <- as.factor(gl(3,3)) > values <- rnorm(9) > dataframe <- data.frame(diagnosis=diagnosis, marker=marker, values=values) > dataframe <- dataframe[c(1:5, 7:9), ] > reshape(dataframe,idvar="diagnosis",direction="wide",timevar="marker") >> I have the problem that I want to transform a dataframe as generated by >> >> diagnosis <- rep(diagnosis[1:3], 3) >> marker <- gl(3,3) >> values <- rnorm(9) >> dataframe <- cbind(diagnosis, marker, values) >> dataframe <- dataframe[c(1:5, 7:9), ] >> >> into a matrix where levels(diagnosis) is indicating the rows of the matrix, >> levels(marker) the columns and values are the actual content of the matrix. >> However, as can been seen in the dataframe, some observations are missing >> and >> should result in <NAs> in the resulting matrix, giving a result like this: >> marker 1 2 3 >> diagnosis1 value value value >> diagnosis2 value value value >> diagnosis3 value NA value >> -- Thorsten Raff 2nd Medical Department, University Hospital Schleswig-Holstein, Campus Kiel Chemnitzstraße 33 24116 Kiel GERMANY phone: +49 431 1697-5234 fax: +49 431 1697-1264 email: t.raff<at>med2.uni-kiel.de web: www.uk-s-h.de
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