问如何从R中的各个子文件夹中包含的文件中堆叠各个栅格层？

EN

#List all my subfolders in my parent folder
list_dirs<- list.dirs(path/parentfolder/, recursive = F) 

for (i in list_dir){

# set the working directory to the subfolder i
setwd(i) 

# List all the files with a certain pattern in the subfolder i
s<- list.files(path=setwd(i), pattern = "cool", recursive=F)

# I do not see how I can create a stack for each of my subfolders here.
#I should have an index i somewhere in the last line.

ss<- stack(s)

}