Removing Only Adjacent Duplicates in Data Frame in R

Question

I have a data frame in R that is supposed to have duplicates. However, there are some duplicates that I would need to remove. In particular, I only want to

Answer 1

Try

 df[with(df, c(x[-1]!= x[-nrow(df)], TRUE)),]
#   x  y
#1  A  1
#2  B  2
#3  C  3
#4  A  4
#5  B  5
#6  C  6
#7  A  7
#9  B  9
#10 C 10

Explanation

Here, we are comparing an element with the element preceding it. This can be done by removing the first element from the column and that column compared with the column from which last element is removed (so that the lengths become equal)

 df$x[-1] #first element removed
 #[1] B C A B C A B B C
 df$x[-nrow(df)]
  #[1] A B C A B C A B B #last element `C` removed

 df$x[-1]!=df$x[-nrow(df)]
 #[1]  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE FALSE  TRUE

In the above, the length is 1 less than the nrow of df as we removed one element. Inorder to compensate that, we can concatenate a TRUE and then use this index for subsetting the dataset.