Thanks, let me try to clarify my question with an example. Suppose I have the following data:
Gender, Major, Course-Grade F, Psy, 3.5 F, Psy, 3.1 M, Hst, 3.7 F, Hst, 3.6 M, Hst, 2.6 M, Eng, 3.9 I want to compute a table like the following: X-axis: Gender Y-axis: Major Cell(x,y) = mean course-grade So for example, with the data above: F M ------------------------ Psy | 3.3 NA Hst | 3.6 3.15 Eng | NA 3.9 If I were doing this in SQL I'd do it with a cross-tab query. But the world of R still has much unfamiliar terrain :) Thanks, Christian On 11/15/06, Jeffrey Robert Spies <[EMAIL PROTECTED]> wrote: > > I'm not sure I understand the question, but you might look into the > following functions: > > unique > heatmap > image > > Again, if I understand the question, you would create a length(unique > (x)) by length(unique(y)) sized matrix, and fill it with appropriate > values of z. Then pass that to heatmap or image. > > Hope that helps--feel free to tell me if I've answered the wrong > question, > > Jeff. > > On Nov 15, 2006, at 8:30 AM, Christian Convey wrote: > > > I'm very new to R, so please forgive me if I just missed the answer in > > existing documentation... > > > > I have a data set with at least three columns, X, Y, and Z. > > > > I want to produce a chart where one axis shows all the unique > > values of X, > > and the other axis shows all the unique values of Y. Each cell > > within the > > chart should contain the result of applying an aggregate function > > (such as > > mean(), for example) to Z value of those rows that are associated > > with that > > cell (via their X and Y values). > > > > Can someone recommend a good way to do this? > > > > Thanks very much, > > Christian > > > > [[alternative HTML version deleted]] > > > > ______________________________________________ > > 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 > > and provide commented, minimal, self-contained, reproducible code. > > [[alternative HTML version deleted]] ______________________________________________ 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 and provide commented, minimal, self-contained, reproducible code.