我们可以使用顺序为每个变化创建组

diff

如果组中有多于1行并更新值，则从每个组中仅选择第一行

stop

在组中持续值。

    
      library(dplyr)
df %>%
   group_by(group = cumsum(c(1, diff(nr) != 1))) %>%
   mutate(stop = last(stop)) %>%
   filter(n() > 1 & row_number() == 1) %>%
   ungroup() %>%
   select(-group)
nr   grp start  stop l1    ratio
     
1    11     1   300   650 +         1
2    36     1  1000  1400 +         0
</code>
  

使用data.table很容易：

    
      DT <- fread(“   nr  grp start stop l1 ratio
            11   1   300  350  +   1.0
            12   1   400  450  -   0.8
            13   1    50  550  +   1.0
            14   1   600  650  -   1.0
            21   1   800  850  -   1.0
            36   1  1000 1050  +   0.0
            37   1  1100 1200  +   0.9
            38   1  1250 1300  -   0.7
            39   1  1350 1400  +   1.0”)
setDT(DT) #if you haven’t imported with fread
create group ID, here for didactic reason
DT[, groups := cumsum(c(TRUE, diff(nr) != 1))]
take first row and replace stop from last row
DT[, if (.N > 1) {
  res <- .SD[1]
  res$stop <- .SD[.N, stop]
  res
  } else NULL, by = groups]
groups nr grp start stop l1 ratio
1:      1 11   1   300  650  +     1
2:      3 36   1  1000 1400  +     0
</code>