用密度曲线叠加直方图
问题描述：
我正在尝试制作密度值的直方图，并将其与密度函数的曲线(不是密度估计值)叠加.
I am trying to make a histogram of density values and overlay that with the curve of a density function (not the density estimate).
使用一个简单的标准法线示例，这里有一些数据:
Using a simple standard normal example, here is some data:
x <- rnorm(1000)
我能做到:
q <- qplot( x, geom="histogram")
q + stat_function( fun = dnorm )
但这给出了直方图的频率而不是密度的比例.使用 ..density.. 我可以在直方图上获得适当的比例:
but this gives the scale of the histogram in frequencies and not densities. with ..density.. I can get the proper scale on the histogram:
q <- qplot( x,..density.., geom="histogram")
q
但是现在这给出了一个错误:
But now this gives an error:
q + stat_function( fun = dnorm )
有什么我没有看到的吗?
Is there something I am not seeing?
另一个问题，有没有办法绘制函数的曲线，比如curve()，但不是作为层?
Another question, is there a way to plot the curve of a function, like curve(), but then not as layer?
答
给你！
# create some data to work with
x = rnorm(1000);
# overlay histogram, empirical density and normal density
p0 = qplot(x, geom = 'blank') +
geom_line(aes(y = ..density.., colour = 'Empirical'), stat = 'density') +
stat_function(fun = dnorm, aes(colour = 'Normal')) +
geom_histogram(aes(y = ..density..), alpha = 0.4) +
scale_colour_manual(name = 'Density', values = c('red', 'blue')) +
theme(legend.position = c(0.85, 0.85))
print(p0)