我有这个数据框
df <- structure(list(word = structure(c(1L, 12L, 23L, 34L, 43L, 44L,
45L, 46L, 47L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 10L, 11L, 13L,
14L, 15L, 16L, 17L, 18L, 19L, 20L, 21L, 22L, 24L, 25L, 26L, 27L,
28L, 29L, 30L, 31L, 32L, 33L, 35L, 36L, 37L, 38L, 39L, 40L, 41L,
42L), .Label = c("wo