在R中按元素拆分字符向量？

Question

Given a vector:

c("kuku", "pupu", "lilu","","ff","rrrr", "", "rrr")

How can I split it by "" ?

To get 3 vectors:

c("kuku", "pupu", "lilu")
c("ff","rrrr")
c("rrr")

Answer 1

We can get the cumulative sum of logical vector to create the grouping index for split

i1 <- v1 == ""
i1
#[1] FALSE FALSE FALSE  TRUE FALSE FALSE  TRUE FALSE


grp <- cumsum(i1)
grp
#[1] 0 0 0 1 1 1 2 2

Note that with cumulative sum, it adds 1 at every TRUE value. Then, we do a subset of the vector to not include the "" . By negating ( ! ) the TRUE beomes FALSE and FALSE -> TRUE.

v1[!i1]
#[1] "kuku" "pupu" "lilu" "ff"   "rrrr" "rrr" 

Similarly, the 'grp' is also subsetted as we want both vectors to be of the same length and do the split

split(v1[!i1], grp[!i1])
#$`0`
#[1] "kuku" "pupu" "lilu"

#$`1`
#[1] "ff"   "rrrr"

#$`2`
#[1] "rrr"