Ordering x-axis on correlation heat map using ggplot

Question

I am trying to create a correlation heat map using ggplot, but I cannot seem to control the order of my variables on the x or y axis. Specifally, ggplot seems to try to order t

Answer 1

Try this if the padded zero solution doesn't fit for your purpose:

cust_breaks<-unique(keep$Var1[order(as.numeric(gsub("x","",keep$Var1)))])

ggplot(keep,aes(Var1,Var2),xlab=NULL,ylab=NULL) + 
  geom_tile(aes(fill = value),colour = "white") + 
  scale_fill_gradient(low = "white",high = "steelblue") + 
  theme(axis.title.x=element_blank(),axis.title.y=element_blank()) +
  scale_x_discrete(limits=cust_breaks) + 
  scale_y_discrete(limits=cust_breaks)

Answer 2

This works for me:

keep$Var1 <- factor(keep$Var1, levels = unique(keep$Var1), ordered = TRUE)
keep$Var2 <- factor(keep$Var2, levels = unique(keep$Var2), ordered = TRUE)

ggplot(keep,aes(Var1,Var2),xlab=NULL,ylab=NULL) + geom_tile(aes(fill = value),colour = "white") + scale_fill_gradient(low = "white",high = "steelblue")+theme(axis.title.x=element_blank(),axis.title.y=element_blank())

Answer 3

For this particular example, one option would be to name your variables x01, x02, etc and then they will order correctly.