r - 将分组数据过滤到分组发生变化的行

Question

使用这些数据(下面使用 dput())，其中 IndIDII 是一个分组列，其中有多个 MigStratFact 观察值每个年。

> head(Dat)
  IndIDII Year MigStratFact
1 BHS_376 2015      MidDist
2 BHS_376 2016      MidDist
3 BHS_376 2017      MidDist
4 BHS_376 2018    ShortDist
5 BHS_378 2015      MidDist
6 BHS_378 2016    ShortDist

我想将 Dat 过滤到 MigStratFact 的 lead() 值与当前值不匹配的行，并且还保留当前字段。

使用下面的代码，对于每个 IndIDII，我可以过滤到 lead(MigStratFact) != MigStratFact 的行，但我不确定如何保留引用(即当前)行。

Dat %>%
  group_by(IndIDII) %>% 
  filter(lead(MigStratFact) != MigStratFact) %>% 
  as.data.frame()

所需的解决方案将过滤到第 3、4、5、6、8、9、11、12、15、16 行。

提前非常感谢

Dat <- structure(list(IndIDII = c("BHS_376", "BHS_376", "BHS_376", "BHS_376", 
    "BHS_378", "BHS_378", "BHS_378", "BHS_391", "BHS_391", "BHS_394", 
    "BHS_394", "BHS_394", "BHS_395", "BHS_395", "BHS_395", "BHS_395"
    ), Year = c("2015", "2016", "2017", "2018", "2015", "2016", "2017", 
    "2015", "2016", "2016", "2017", "2018", "2015", "2016", "2017", 
    "2018"), MigStratFact = structure(c(3L, 3L, 3L, 2L, 3L, 2L, 2L, 
    2L, 3L, 3L, 3L, 2L, 3L, 3L, 3L, 2L), .Label = c("Resident", "ShortDist", 
    "MidDist", "LongDist"), class = "factor")), class = "data.frame", row.names = c(NA, 
    -16L))

Answer 1

尝试更改为

Dat %>%
  group_by(IndIDII) %>% 
  filter(lead(MigStratFact) != MigStratFact | lag(MigStratFact) != MigStratFact)
#    IndIDII Year MigStratFact
# 1  BHS_376 2017      MidDist
# 2  BHS_376 2018    ShortDist
# 3  BHS_378 2015      MidDist
# 4  BHS_378 2016    ShortDist
# 5  BHS_391 2015    ShortDist
# 6  BHS_391 2016      MidDist
# 7  BHS_394 2017      MidDist
# 8  BHS_394 2018    ShortDist
# 9  BHS_395 2017      MidDist
# 10 BHS_395 2018    ShortDist