Hi there, I think you're on the right track in a few places.
A good place to start would be to read all of your files in and store as a list, something like:
library(purrr)
my_files <- list.files(
path = "path/to/your/files/",
pattern = "OTT_SAT",
full.names = TRUE
)
# use appropriate read_*() function for your file type
df_list <- map(my_files, read_csv)
After that it can be as simple as:
map_dbl(
.x = df_list,
.f = ~mean(is.na(.x[["desired_column"]]))
)
This will get you what you asked for. I would recommend you check out this article on nesting data as a thought starter. Getting comfortable with list-columns is really a game changer, and learning how to connect the {tidyr}, {dplyr} and {purrr} packages is a very useful skill to have.