How to filter data without losing NA rows using dplyr

If you want to keep NAs created by the filter condition you can simply turn the condition NAs into TRUEs using replace_na from tidyr.

a <- data.frame(col = c("hello", NA, "str"))
a %>% filter((col != "str") %>% replace_na(TRUE))

The documentation for dplyr::filter says... "Unlike base subsetting, rows where the condition evaluates to NA are dropped."

NA != "str" evaluates to NA so is dropped by filter.

!grepl("str", NA) returns TRUE, so is kept.

If you want filter to keep NA, you could do filter(is.na(col)|col!="str")