基于块长度向量的分裂向量

Question

我有一个二进制数向量。我知道每组对象的连续长度；我如何根据该信息进行拆分（没有 for 循环）？

x = c("1","0","1","0","0","0","0","0","1")
.length = c(group1 = 2,group2=4, group3=3)

x是我需要拆分的二进制数向量。 .length 是我得到的信息。 .length 本质上告诉我第一组有 2 个元素，它们是前两个元素 1,0。第二组有 4 个元素，包含第 1 组数字后的 4 个数字，1,0,0,0，等等

有没有办法将其拆分并将拆分后的项目返回到列表中？

丑陋的方法是通过 for 循环跟踪当前的 cumsum，但我正在寻找一种更优雅的方法（如果有的话）。

Answer 1

可以使用rep设置分割变量，使用split

x = c("1","0","1","0","0","0","0","0","1")
.length = c(group1 = 2,group2=4, group3=3)

split(x, rep.int(seq_along(.length), .length))
# $`1`
# [1] "1" "0"
#
# $`2`
# [1] "1" "0" "0" "0"
#
# $`3`
# [1] "0" "0" "1"

如果您想将组名带到拆分列表中，您可以更改rep以复制名称

split(x, rep.int(names(.length), .length))
# $group1
# [1] "1" "0"
#
# $group2
# [1] "1" "0" "0" "0"
#
# $group3
# [1] "0" "0" "1"

Answer 2

另一种选择是

split(x,cumsum(sequence(.length)==1))
#$`1`
#[1] "1" "0"

#$`2`
#[1] "1" "0" "0" "0"

#$`3`
#[1] "0" "0" "1"

获得group names

split(x, sub('.$', '', names(sequence(.length))))
#$group1
#[1] "1" "0"

#$group2
#[1] "1" "0" "0" "0"

#$group3
#[1] "0" "0" "1"

基于块长度向量的分裂向量

Splitting vector based on vector of chunk-lengths

r

chunks