R: define distinct pattern from values of multiple variables [duplicate]

Answer 1

Use rleid in data.table.

setDT(df)[,pattern:=rleid(x,y)]

Answer 2

You can use dplyr::group_indices():

NSE version

group_indices(df, x, y)
# [1] 1 1 2 3 4 4

SE version

group_indices_(df, .dots = names(df))
# [1] 1 1 2 3 4 4

The unfortunate side of this function is that it doesn't work with mutate function (yet), so you have to use it as:

df$pattern <- group_indices(df, x, y)

---

From the linked answer, it seems that even though the non-standard evaluation version doesn't work with mutate, the standard evaluation version does:

df %>% mutate(pattern = group_indices_(df, .dots = c('x', 'y')))

Answer 3

In base we can paste together the relevant columns, convert them to character, and then get the integer code of the factor:

as.numeric(as.factor(paste(df$x,'_',df$y)))

for the data above it is half the speed of the dplyr solution (unclear how it will scale):

microbenchmark::microbenchmark(as.numeric(as.factor(paste(z$x,'_',z$y))), group_indices(df, x, y))
Unit: microseconds
                                        expr     min       lq     mean  median       uq     max neval cld
 as.numeric(as.factor(paste(df$x, "_", df$y))) 150.913 153.9855 162.5637 159.745 165.8890 258.817   100  a 
                     group_indices(df, x, y) 322.945 327.3610 339.4574 337.922 340.4175 567.938   100   b