Split vector separated by n zeros into different group

Question

I have a vector x

x = c(1, 1, 2.00005, 1, 1, 0, 0, 0, 0, 1, 2, 0, 3, 4, 0, 0, 0, 0, 1, 2, 3, 1, 3)

I need to split values sepa

Answer 1

Here is a method with rle, split, and lapply

# get RLE
temp <- rle(x)
# replace values with grouping variables
temp$values <- cumsum(temp$values == 0 & temp$lengths > 2)

# split on group and lapply through, dropping 0s at beginning which are start of each group
lapply(split(x, inverse.rle(temp)), function(y) y[cummax(y) > 0])
$`0`
[1] 1.00000 1.00000 2.00005 1.00000 1.00000

$`1`
[1] 1 2 0 3 4

$`2`
[1] 1 2 3 1 3

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A second method without lapply is as follows

# get RLE
temp <- rle(x)
# get positions of 0s that force grouping
changes <- which(temp$values == 0 & temp$lengths > 2)
# get group indicators
temp$values <- cumsum(temp$values == 0 & temp$lengths > 2)
# make 0s a new group
temp$values[changes] <- max(temp$values) + 1L

# create list
split(x, inverse.rle(temp))
$`0`
[1] 1.00000 1.00000 2.00005 1.00000 1.00000

$`1`
[1] 1 2 0 3 4

$`2`
[1] 1 2 3 1 3

$`3`
[1] 0 0 0 0 0 0 0 0

Finally, you'd just drop the last list item, like head(split(x, inverse.rle(temp)), -1).