How do I plot a npdensity object with ggplot?

Question

How do I plot a npdensity object with ggplot, like one from the output of npudens?

Answer 1

Use geom_line together with the built-in functionality of predict with npdensity.

df <- data.frame(x = rnorm(1000))
df.kde <- npudens(~x, data=df)
ggplot(df, aes(x)) 
  + stat_function(fun = function(new.x) predict(df.kde, newdata=data.frame(x=new.x)))

If you have evaluated at enough x points such that the graph looks good, you can get away with using eval$x and dens.

geom_line(aes(df.kde$eval$x, df.kde$dens))