直方图y轴在散点图中缩放为1，y轴更大

Question

Alternate title: How can I scale my y-axis for the histogram only to range 0-1?

Horrible question title, so example to demonstrate. The data here are set so that the ranges are nearly equal to my data ranges on the y-axis... about 0 to 3.5.

library(ggplot2)
x<-runif(100)*200
y<-runif(100)*3
xy<-data.frame(x,y)

p <- ggplot(xy) + theme_bw()
p + geom_point(aes(x, y)) + 
  geom_histogram(aes(x), alpha=1/10)

I want the histogram 'y-range' to be scaled to a max of 1. The first part of this answer shows an example, saying:

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You were close, but need to use (..density..)*binwidth rather than ..count../sum(..count..)

# Your data:
all <- data.frame(fill=rep(LETTERS[1:4],c(26,24,23,29)),
                  Events=c(1,1,3,1,1,6,2,1,1,2,1,1,1,1,5,1,2,2,1,1,1,1,2,1,2,1,2,3,1,3,2,5,1,1,1,2,1,1,1,1,1,1,1,1,1,4,3,3,5,3,1,2,2,3,3,9,8,1,1,2,2,1,2,39,43,194,129,186,1,2,7,4,1,12,3,2,3,8,20,5,1,4,9,51,12,7,6,7,7,9,17,18,8,7,6,10,27,11,21,89,47,1))

bw <- 20 # set the binwidth
# plot
p1<-ggplot(all,aes(x=Events, fill=fill)) + 
  geom_histogram(aes(y=(..density..)*bw), position='dodge', binwidth=bw)
p1

---

but it doesn't work for me, failing with an error about there being no variable 'bw':

bw <- 30
p <- ggplot(xy) + theme_bw()
p + geom_point(aes(x, y)) + 
  geom_histogram(aes(x=x, y=..density.. * bw), alpha=1/10)

Error in eval(expr, envir, enclos) : object 'bw' not found

Answer 1

Goodness me, I found the notation I needed...

y=..ncount.. 

From: Normalizing y-axis in histograms in R ggplot to proportion