I would like to use Greek characters, Latin characters and the percent sign in the facet labels of a ggplot2 bar chart. Greek characters can be done with 'facet_grid(.~variable, labeller=label_parsed)':

    a<-c("Delta~V","VarcoV","Delta~V","VarcoV")
    b<-c(1,2,3,4)
    d<-c("one","one","two","two")
    mydata<-data.frame(cbind(b,a,d))
    ggplot(mydata,aes(x=d,y=b))+facet_grid(.~a, labeller=label_parsed)+geom_bar(stat="identity")

Now I also want to add a facet label that includes % and a Latin character:

    a<-c("Delta~V","VarcoV","%V","Delta~V","VarcoV","%V")
    b<-c(1,2,3,4,5,6)
    d<-c("one","one","one","two","two","two")
    mydata<-data.frame(cbind(b,a,d))
    ggplot(mydata,aes(x=d,y=b))+facet_grid(.~a, labeller= label_parsed)+geom_bar(stat="identity")

This produces the following error:

    Error in parse(text = x) : <text>:1:1: unexpected input
    1: %V
       ^

Any ideas how to include the percent sign?

r ggplot2 bar-chart plotmath
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