on 02/12/2009 06:35 AM R User R User wrote: > Hi all, > I'd be grateful for your help. I am a new user struggling with a barplot > issue. > > I am plotting categories (X axis) and their mean count (Y axies) with > barplot(). > > The first call to barplot works fine. > > I remove records from the dataframe using final=[!final$varname == "some > value",] > > I echo the dataframe and the records are no longer in the dataframe. > > When I call plot again however, the X axis still contains the removed > category values albeit with a count of 0. > > How can I stop the removed categories appearing in the barplot? Are they > stored globally after the first barplot call? > > thanks in advance for your help. > > R
When you subset a factor, the unused levels are not removed by default. This is intentional to preserve these characteristics for subsequent operations such as modeling. You are presumably using something like: table(final$varname) to create the counts used in barplot(). As an example, using the iris dataset: > table(iris$Species) setosa versicolor virginica 50 50 50 iris2 <- subset(iris, Species != "setosa") > table(iris2$Species) setosa versicolor virginica 0 50 50 Note that even though I removed records from iris where Species == "setosa", it still shows in the table. You would need to do the following: iris2$Species <- factor(iris2$Species) > table(iris2$Species) versicolor virginica 50 50 Using factor() on the column removes the unused levels. See ?"[.factor" for more information. HTH, Marc Schwartz ______________________________________________ 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.