Remove consecutive duplicates from dataframe

Question

I have a data frame that I want to remove duplicates that are consecutive (in base). I know rle may be helpful here but can\'t think of how to use it. The exa

Answer 1

Here a fast solution using filter

dat[(filter(dat,c(-1,1))!= 0)[,1],]
     v1   v2
1     A  Jan
3     E  May
4     B  Feb
7     A  Jan
8     D  Apr
10    A  Mar
11    B  Feb
12    E  May
15    B  Feb
18    C  Mar
19    D  Apr
NA <NA> <NA>

You need to add the last value of the original data to the result.

Answer 2

Here's a way, not with rle, but a way none-the-less:

dat[with(dat, c(TRUE, diff(as.numeric(interaction(v1, v2))) != 0)), ]

This assumes you're using factor columns, as your sample data implies.

Answer 3

Using rle I came up with this

ind <- cumsum(rle(as.character(dat$v1))$length)
dat[ind, ]

ind indicates either the first or the last of consecutive entries.

EDIT:

A simple solution to Matthews comment would be

dat[15, 2] <- "May"
dat[cumsum(rle(paste0(dat$v1, dat$v2))$length), ]