loess vs. rolling mean vs. simple group means

library(ggplot2)
library(dplyr)
library(zoo) # for rollmean()

d_mean = (diamonds 
	%>% mutate(price=round(price, -2))
	%>% group_by(price)
	%>% mutate(mean_x = mean(x)))

d_roll = (diamonds
	%>% arrange(price)
	%>% mutate(rollmean_x = rollmean(
		x=x,
		k=floor(nrow(diamonds)/10),
		align="center",
		fill=NA)))

(ggplot(diamonds, aes(x=price, y=x))
+geom_point()
+geom_point(aes(y=mean_x), data=d_mean, color="red")
+geom_point(aes(y=rollmean_x), data=d_roll, color="goldenrod")
+geom_smooth(method="loess", span=0.1)
)