ggplot2 - highlight min/max bar
data= data.frame( Name = c("Joe","Jane", "John") , Value = c(3,2,1) )
ggplot(data=data)+geom_bar(aes_string(x="Name",y="Value"), stat="identity" )

p <- ggplot(data=data)+
     geom_bar(aes(x=Name, y=Value), stat="identity") +
     geom_bar(data=subset(data, Value==min(Value)), aes(Name, Value),
              fill="red", stat="identity") +
     geom_bar(data=subset(data, Value==max(Value)), aes(Name, Value),
              fill="green", stat="identity")
print(p)

ggplot(data, aes(Name, Value)) +
 geom_bar(stat = 'identity') +
 geom_bar(stat = 'identity', aes(fill = factor(Value)),
   subset = .(Value %in% range(Value))) +
 scale_fill_manual(values = c('red', 'green'))

ggplot(data=data) +
  geom_bar(aes_string(x="Name",y="Value", fill='factor(ifelse(Value==max(Value), 3, ifelse(Value==min(Value), 2, 1)))'), stat="identity" ) +
  scale_fill_manual(values=c('gray20', 'red', 'green'), legend=F)

ggplot(data, aes(Name, Value, stat = "identity")) +
  geom_bar() +
  geom_bar(data = data[which.min(data$Value),], fill = "red") +
  geom_bar(data = data[which.max(data$Value),], fill = "green")