在R中以NA分割单列数据帧

Question

I have a large data set that I want to split into individual units. Right now, these unit barriers are marked by NA, but how do I split them? Sample set:

df=matrix(c(1,2,3,4,NA,6,7,8,NA,10,11,12),ncol=1,byrow=TRUE)

gives us

       [,1]
 [1,]    1
 [2,]    2
 [3,]    3
 [4,]    4
 [5,]   NA
 [6,]    6
 [7,]    7
 [8,]    8
 [9,]   NA
[10,]    10
[11,]    11
[12,]    12

I would like these three stored in separate variables, such that

a
      [,1]
 [1,]    1
 [2,]    2
 [3,]    3
 [4,]    4
b
      [,1]
 [1,]    6
 [2,]    7
 [3,]    8
c
      [,1]
 [1,]    10
 [2,]    11
 [3,]    12

Does this make sense? Thanks.

Answer 1

One line solution using split and cumsum after removing missing values:

 split(df[!is.na(df)],cumsum(is.na(df))[!is.na(df)])
$`0`
[1] 1 2 3 4

$`1`
[1] 6 7 8

$`2`
[1] 10 11 12

Answer 2

I wasn't sure if by "data set" you meant a true matrix or a data.frame. Here's a data.frame example, a matrix would be similar

df <- data.frame(a=c(1,2,3,4,NA,6,7,8,NA,10,11,12))
gg <- ifelse(is.na(df$a),NA, cumsum(is.na(df$a)))
split(df, gg)

We just use gg as a new variable to count up every time we see an NA so we can divide the sections into groups. We also retain the NA values to drop them for the splitting. And finally split() with this new categorical variable does what we want.

$`0`
  a
1 1
2 2
3 3
4 4

$`1`
  a
6 6
7 7
8 8

$`2`
    a
10 10
11 11
12 12