Valmiera Change the label of legend not by changing the data.

http://adsecurite.fr/?seledka=mettre-une-fausse-photo-sur-un-site-de-rencontre&93f=48 # data grp <- gl(n=4,k=20,labels=c("group a","group b","group c", "group d")) value <- runif(n=80, min=10, max=150) outcome <- cut(value,2) data <- data.frame(grp,value,outcome) # Option 1 # breaks should be exactly the same as the levels of the factor ggplot(data, aes(grp, fill=outcome)) + geom_bar() +xlab("group") + ylab("number of subjects") + scale_fill_discrete("Serologic response", breaks=c("(12.1,79.7]","(79.7,147]"), # should be the same as the levels of the factor labels=c("double negative", "positive for a and/or b") ) # Option 2 # simpler because factor() takes care of the levels of the factor ggplot(data, aes(grp, fill=factor(outcome,labels=c("double negative","positive for a")))) + geom_bar() +xlab("group") +ylab("number of subjects") + labs(fill="Serologic response")

http://stackoverflow.com/questions/7323191/how-do-i-manually-change-the-key-labels-in-a-legend-in-ggplot2