How can I use Theil-Sen method with geom_smooth

Question

I am trying to implement a theil-sen operator in ggplot's geom_smooth. In an ideal world it would read something like: geom_smooth(..., methods= "mblm"). I cannot seem to find an answer to this, nor can I figure out how I would customize the methods for this. Any advice, pointers, or code help would be greatly appreciated.

I would like to effectively replacing add "mblm" to the methods options in geom_smooth:

library(tidyverse)
library(mblm)


# Option 1 - adding 'mblm' into the methods directly
ggplot(mtcars, aes(qsec, wt))+   
geom_point() +     
geom_smooth(method='mblm')

# Option 2 - defining the Theil-Sen function outside
ts_fit <- mblm(qsec ~ wt, data = mtcars)
ggplot(mtcars, aes(qsec, wt))+   
geom_point() +     
geom_smooth( alpha=0,method=ts_fit)

Neither works. I generate the warning Warning message: Computation failed in stat_smooth(): unused argument (weights = weight), which is essential an error in the geom_smooth line. Any help would be appreciated.

Thanks in advance, Nate

Answer 1

I figured it out. Here is the answer for completion.

# Option 2 - defining the Theil-Sen function outside
ts_fit <- mblm(qsec ~ wt, data = mtcars)

ggplot(mtcars, aes(qsec, wt))+   
geom_point() +     
  geom_abline(intercept = coef(ts_fit)[1], slope = coef(ts_fit)[2])

Update: Figured out a more repeatable way to accomplish this.

sen <- function(..., weights = NULL) {
  mblm::mblm(...)
}

mtcars %>% 
  ggplot(aes(qsec, wt)) +   
  geom_point() +     
  geom_smooth(method = sen)