R version 4.4.0 alpha (2024-04-02 r86304 ucrt)
Copyright (C) 2024 The R Foundation for Statistical Computing
Platform: x86_64-w64-mingw32/x64

R is free software and comes with ABSOLUTELY NO WARRANTY.
You are welcome to redistribute it under certain conditions.
Type 'license()' or 'licence()' for distribution details.

R is a collaborative project with many contributors.
Type 'contributors()' for more information and
'citation()' on how to cite R or R packages in publications.

Type 'demo()' for some demos, 'help()' for on-line help, or
'help.start()' for an HTML browser interface to help.
Type 'q()' to quit R.

> # https://github.com/r-spatial/stars/issues/295
> suppressPackageStartupMessages(library(stars))
> raw <- read_stars(system.file("nc/bcsd_obs_1999.nc", package = "stars"))
pr, tas, 
> foo <- function(x, idx) stats::lowess(idx, x)$y
> 
> timeline <- st_get_dimension_values(raw, "time")
> smooth = st_apply(raw,
+ 	MARGIN = c("x", "y"),
+ 	FUN = foo,
+ 	idx = st_get_dimension_values(raw, "time")
+ )
> 
> st_set_dimensions(smooth,
+ 	which = "foo",
+ 	values = st_get_dimension_values(raw, "time"),
+ 	names = "time"
+ )
stars object with 3 dimensions and 2 attributes
attribute(s):
          Min.   1st Qu.   Median     Mean   3rd Qu.     Max. NA's
pr   16.133519 70.371665 84.55774 87.72969 101.94830 278.6427 7116
tas  -2.354958  9.632157 15.32671 14.61650  19.99331  24.7976 7116
dimension(s):
     from to offset  delta  refsys                    values x/y
time    1 12     NA     NA POSIXct 1999-01-31,...,1999-12-31    
x       1 81    -85  0.125      NA                      NULL [x]
y       1 33  37.12 -0.125      NA                      NULL [y]
> 
> raw %>%
+   st_apply(MARGIN = c("x", "y"), FUN = foo, idx = timeline) %>%
+   st_set_dimensions("foo", st_dimensions(raw)["time"])
stars object with 3 dimensions and 2 attributes
attribute(s):
          Min.   1st Qu.   Median     Mean   3rd Qu.     Max. NA's
pr   16.133519 70.371665 84.55774 87.72969 101.94830 278.6427 7116
tas  -2.354958  9.632157 15.32671 14.61650  19.99331  24.7976 7116
dimension(s):
     from to offset  delta  refsys                    values x/y
time    1 12     NA     NA POSIXct 1999-01-31,...,1999-12-31    
x       1 81    -85  0.125      NA                      NULL [x]
y       1 33  37.12 -0.125      NA                      NULL [y]
> 
> proc.time()
   user  system elapsed 
   1.23    0.14    1.34