ggplot2 Transfer calculated value from smooth to linerange

[zhangdafeng]

Dear sir,
I have a problem about ggplot2.
I want to connect data point with ols result via vertical line, like The code listed below.
Can I transfer ..y.., the value calculated by stat_smooth, to geom_linerange directly?
I tried stat_smooth(...,geom="linerange",mapping(aes(ymin=pmin(myy,..y..),ymax=pmax(myy,..y..)) but it is not the result I want.
Thanks for any help.

library(ggplot2)
df<-data.frame(myx=1:10,myy=c(1:10)*5+2*rnorm(10,0,1))
lm.fit<-lm("myy~myx",data=df)
pred<-predict(lm.fit)
ggplot(df,aes(myx,myy))+geom_point()+geom_smooth(method="lm",se=FALSE)+
geom_linerange(mapping=aes(ymin=pmin(myy,pred),ymax=pmax(myy,pred)))

[FJCC]

It is not clear to me why the result is not what you want. I understand that you want a vertical line from each point to the fit line and that is what I see in your plot. Can you explain what you want to be different?
Here is another version of your code that is a little neater, in my opinion.

library(ggplot2)
suppressPackageStartupMessages(library(dplyr))
set.seed(1234)
df<-data.frame(myx=1:10,myy=c(1:10)*5+5*rnorm(10,0,1))
lm.fit<-lm("myy~myx",data=df)
df <- df %>% mutate(PredValue = predict(lm.fit))
df <- df %>% mutate(ymax = pmax(myy, PredValue), ymin = pmin(myy, PredValue))
ggplot(df,aes(myx,myy))+ geom_point()+ geom_smooth(method="lm",se=FALSE)+
  geom_linerange(mapping=aes(ymin=ymin,ymax=ymax))

^{Created on 2019-05-27 by the reprex package (v0.2.1)}

[zhangdafeng]

Thanks for you help and reply.
The following code generate the same OLS fitted value:

1. predict(lm("myy~myx",data=df))
2. geom_smooth(mapping=aes(x=myx,y=myy),method="lm")

For the second code, I mean that ..y.. calculated by stat_smooth is the OLS fitted value.
To draw a vertical line, the OLS fitted value was calculated twice. Can I draw the vertical line Completely with ggplot only?

[FJCC]

I cannot find a way to use the calculated values from geom_smooth in geom_linerange. If the main concern is to calculate the fit only once, I would store the predictions from the regression in the data frame and not use geom_smooth at all.

I modified my code a bit based on the answer you got on Stack Overflow.

Transfer calculated value from stat_smooth to other geom like linerange

library(ggplot2)
suppressPackageStartupMessages(library(dplyr))
set.seed(1234)
df<-data.frame(myx=1:10,myy=c(1:10)*5+5*rnorm(10,0,1))
lm.fit<-lm("myy~myx",data=df)
df <- df %>% mutate(PredValue = predict(lm.fit))
df <- df %>% mutate(ymax = PredValue, ymin = myy)
ggplot(df,aes(myx,myy))+ geom_point()+ geom_line(aes(y = PredValue))+
  geom_linerange(mapping=aes(ymin=ymin,ymax=ymax))

^{Created on 2019-05-28 by the reprex package (v0.2.1)}

[zhangdafeng]

Thanks for you help and reply.
Maybe the best way is what you said. It is flexible and can be apply to any situation.
Thanks again.