df1 <- data.frame(
id = c(1, 2, 3, 1, 3),
item1 = c(NA, 1, 1, 2, 3),
item2 = c(NA, 1, 1, 2, 3),
item3 = c(NA, 1, 1, 2, 3)
)
extract_duplicates(df1, id = "id")
# Filter to exclude duplicates
df2 <- df1[-c(1, 5), ]
df2
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