R - delete consecutive (ONLY) duplicates

Question

I need to eliminate rows from a data frame based on the repetition of values in a given column, but only those that are consecutive. For example, for the following data fram

Answer 1

A cheap solution with dplyr that I could think of:

Method:

library(dplyr)
df %>% 
  mutate(id = lag(x, 1), 
         decision = if_else(x != id, 1, 0), 
         final = lead(decision, 1, default = 1)) %>% 
  filter(final == 1) %>% 
  select(-id, -decision, -final)

Output:

  x  y z
1 1 30 3
2 2 49 5
3 4 13 6
4 2 49 8
5 1 30 9

This will even work if your data has the same x value at the bottom

New Input:

df2 <- df %>% add_row(x = 1, y = 10, z = 12)
df2

   x  y  z
1  1 10  1
2  1 11  2
3  1 30  3
4  2 12  4
5  2 49  5
6  4 13  6
7  2 12  7
8  2 49  8
9  1 30  9
10 1 10 12

Use same method:

df2 %>% 
  mutate(id = lag(x, 1), 
         decision = if_else(x != id, 1, 0), 
         final = lead(decision, 1, default = 1)) %>% 
  filter(final == 1) %>% 
  select(-id, -decision, -final)

New Output:

  x  y  z
1 1 30  3
2 2 49  5
3 4 13  6
4 2 49  8
5 1 10 12