R ggplot：无法使用多面图更改y轴比例范围

Question

I have a simple problem but I can't figure out why it won't work -> I can't adjust the y scale range on my faceted bar plot:

# Data #

df<-as.data.frame(c("x","y","z","x","y","z","x","y","z","x","y","z"))
colnames(df)<-"x"
df$y<-c(10,15,20,5,25,45,10,10,20,40,20,5)
df$facet<-c(1,1,1,1,1,1,2,2,2,2,2,2)
df$group<-c("A","A","A","B","B","B","A","A","A","B","B","B")

# Plot #

ggplot(df, aes(x=x, y=y, fill=group)) + 
  facet_grid( ~ facet) +
  scale_fill_manual(values=c("blue", "red")) +
  geom_bar(position="dodge", stat="identity") +
  theme(strip.text = element_text(face="bold", size=rel(1)),
        strip.background = element_rect(fill="white", colour="white", size=1)) +
  theme(panel.margin = unit(1, "lines")) +
  scale_x_discrete(expand = c(0, 0)) +
  theme(panel.grid.major.x = element_blank()) + theme(axis.ticks.x = element_blank()) +
  theme(legend.background=element_blank()) +
  scale_y_continuous("%", breaks=seq(0, 50, 10), minor_breaks=seq(0,50,5), expand = c(0, 0))

I would like the y-axis to go upto 50 but using scale_y_continuous strangely does not work, producing this result:

Answer 1

You need to add a limits argument in your scale_y_continuous :

scale_y_continuous("%", limits=c(0,50), breaks=seq(0, 50, 10), minor_breaks=seq(0,50,5), expand = c(0, 0))

Otherwise you just define the breaks position, not the axis values range.