Sequence reduction in R

2019-05-06 23:33发布

Assume you have a vector like so:

v <- c(1,1,1,2,2,2,2,1,1,3,3,3,3)

How can it be best reduced to a data.frame like this?

v.df <- data.frame(value=c(1,2,1,3),repetitions=c(3,4,2,4))

In a procedural language I might just iterate through a loop and build the data.frame as I go, but with a large dataset in R such an approach is inefficient. Any advice?

2条回答
你好瞎i
2楼-- · 2019-05-07 00:13

or more simply

data.frame(rle(v)[])
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仙女界的扛把子
3楼-- · 2019-05-07 00:19
with(rle(v), data.frame(values, lengths))

should get you what you need.

values lengths
     1       3
     2       4
     1       2
     3       4
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