How to force a y axis to minimum and maximum range in R?

Question

If you look at the graph below (y axis), you will notice that the scale is from 0 to 0.20. I have other histograms where the range is from 0 to 0.4. I want to make all of them consistent from 0 to 1 and display the y axis from 0 to 1.

conne <- file("C:Aisdefined.bin","rb")
sd    <- readBin(conne, numeric(), size=4,  n=1440*720, signed=TRUE)
y     <- t(matrix((data=sd), ncol=1440, nrow=720))
r     <- raster(y)
f     <- hist(y, breaks=10,main="sm")

f$counts <- f$counts/sum(f$counts)
dat <- data.frame(counts= f$counts,breaks = f$mids)
ggplot(dat, aes(x = breaks, y = counts, fill =counts)) + 
   geom_bar(stat = "identity",alpha = 0.8) +
   xlab("Pearson correlation")+ ylab("Frequency") + 
   scale_x_continuous(breaks = seq(-1,1,0.250), labels = seq(-1,1,0.250)) +
   ggtitle("2011") + theme(axis.title.x = element_text(size = 20)) + 
   theme(axis.title.y = element_text(size = 20)) + 
   theme(text = element_text(size=20), 
   axis.text.x = element_text(angle = 90, vjust=1,colour="black"), 
   axis.text.y = element_text(colour="black")) + 
   theme(plot.title = element_text(size = rel(2.5))) + 
   scale_fill_gradientn(colours = "black")

Answer 1

Just add:

+ coord_cartesian(ylim=c(0,1))