Hi: Here's a way you could do it entirely within ggplot2. The annotation functions have a parse = argument which allows you to pass character string representations of math expressions, but there is no such thing in the scale functions, so you need a different approach.
library(ggplot2) df <- data.frame(vis=c(0,0,1,1) , count=c(10,15,20,10) , grp=c(0,1,0,1)) # Generate a list of expressions that will become the legend labels lbs <- list(expression(x <= 10), expression(x > 10)) ggplot(df, aes(x = factor(vis), y=count , fill=factor(grp))) + geom_bar(stat ="identity") + scale_fill_manual(breaks = levels(factor(df$grp)), values = c("blue", "orange"), labels = lbs) The specifications in scale_fill_manual() are: - breaks: the values to go on the horizontal axis - values: the vector of fill colors for each level of grp - labels: the legend labels Notice that the labels = takes a list of expressions as its argument. This approach gives you more control over the legend and choice of fill colors at the expense of a couple of lines of code. To change the axis and legend titles, one can use the labs() function; e.g., last_plot() + labs(x = "Visibility", y = "Frequency", fill = "Threshold") Dennis On Thu, Mar 28, 2013 at 2:22 PM, soon yi <soon...@ymail.com> wrote: > Hi > > I am trying to add a less than equal sign to a plot. I have previously done > this using unicode but is not working in this instance. Any suggestions > would be great > > thanks > > example code: > > library(ggplot2) > df<-data.frame(vis=c(0,0,1,1) , count=c(10,15,20,10) , grp=c(0,1,0,1)) > df$grp <-factor(df$grp ,levels=c(0,1) , labels =c("x \u2265 10" , "x > 10")) > ggplot(df, aes(x = factor(vis), y=count , fill=grp)) + geom_bar(stat = > "identity") > > > > > -- > View this message in context: > http://r.789695.n4.nabble.com/ggplot2-less-than-equal-sign-tp4662784.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.