I'm learning ggplot and am a little confused. Sometimes discrete scales work like I'd expect, and sometimes they don't. For example...
This works exactly like one would expect: df<-data.frame(names=c("Bob","Mary","Joe","Bob","Bob")) ggplot(df,aes(names))+geom_histogram() But this yields an error: ggplot(df,aes(names))+geom_histogram()+xlim("Bob") Error in data.frame(count = as.numeric(tapply(weight, bins, sum, na.rm = TRUE))$ arguments imply differing number of rows: 0, 1 ...as does this: ggplot(df,aes(names))+geom_histogram()+xlim("Bob","Mary") ... but this works fine: ggplot(df,aes(names))+geom_histogram()+xlim("Bob","Mary","Joe") ... and curiously, so does this: ggplot(df,aes(names))+geom_histogram()+xlim("Bob","Mary","Joe","Frank") ... and even more confusingly, this works perfectly: ggplot(df,aes(names,..density..,group=1))+geom_histogram()+xlim("Bob","Mary") This feels like a bug, but perhaps I'm doing something dumb. Can anyone clarify? And while I have your attention: as a ggplot novice, I often find myself getting cryptic error messages like the one above. Nearly always this is because I'm asking it to do something unreasonable, but it often takes me quite a long time to figure out my error. Does anyone have general tips for debugging ggplot commands? Anything better than summary(p)? Thanks very much for your help, -J [[alternative HTML version deleted]] ______________________________________________ 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.