I’d like to draw linear and quadratic regression line per group (data is different).
For example, I make a graph like below.
x=rep(c(0,40,80,120,160),time=2)
y=c(16,21,22,26,35,29,44,72,61,54)
group=rep(c("B","A"),each=5)
dataA=data.frame(x,y,group)
ggplot(data=dataA, aes(x=x, y=y))+
stat_smooth(aes(group=group, color=group),
method='lm', linetype=1, se=FALSE,
formula=y~x, linewidth=0.5) +
geom_point(aes(fill=group, shape=group), color="black", size=4) +
scale_color_manual(values=c("Dark red","grey15"))+
scale_fill_manual(values=c("Dark red","grey15"))+
scale_shape_manual(values=c(24,25))+
scale_x_continuous(breaks=seq(0,160,40), limits = c(0,160)) +
scale_y_continuous(breaks=seq(0,80,20), limits = c(0,80)) +
theme_classic(base_size=20, base_family="serif")+
theme(legend.position=c(0.89,0.08),
legend.title=element_blank(),
legend.key=element_rect(color=alpha("grey",.05),
fill=alpha("grey",.05)),
legend.background= element_rect(fill=alpha("grey",.05)),
strip.background = element_rect(color="white",
linewidth=0.5,linetype="solid"),
axis.line=element_line(linewidth=0.5, colour="black"))+
windows(width=5.5, height=5)
Then, I think group A is better to show quadratic regression. In this case, how can I draw two independent regression graph (Group A: quadratic, Group B: linear)?
Always many thanks,
>Solution :
One way is to use two geom_smooth() and filter dataA by group:
library(dplyr)
library(ggplot2)
dataA %>%
ggplot(aes(x, y)) +
geom_point(aes(color = group)) +
geom_smooth(data = filter(dataA, group == "A"),
method = "lm",
formula = y ~ x + I(x^2),
aes(color = group),
se = FALSE) +
geom_smooth(data = filter(dataA, group == "B"),
method = "lm",
aes(color = group),
se = FALSE) +
theme_bw()
Result:
