Filter the samples
Examples
# subset urt to keep only nasopharynx samples
urt_nf <- urt %>% filter_samples(location == "NF")
# subset urt to keep only samples from plate 1 and 2
urt_plate_1_2 <- urt %>% filter_samples(plate %in% c(1, 2))
# subset the blanks in leaf
leaf_blanks <- leaf %>% filter_samples(startsWith(description, "BLANK"))