Try this:
a <- data.frame(timestamp=c(3,5,8), mylabel=c("abc","def","ghi"))
b <- data.frame(timestamp=c(1:10))
txt <- as.character(a$mylabel)
nrepeat <- diff(c(a$timestamp,nrow(b)))
b$mylabel <- c( rep(NA, a$timestamp[1]), rep(txt,
diff(c(a$timestamp,nrow(b)))) )
greetings,
Remko
-------------------------------------------------
Remko Duursma
Research Lecturer
Centre for Plants and the Environment
University of Western Sydney
Hawkesbury Campus
Richmond NSW 2753
Dept of Biological Science
Macquarie University
North Ryde NSW 2109
Australia
Mobile: +61 (0)422 096908
www.remkoduursma.com
On Wed, Jul 14, 2010 at 3:04 PM, Ralf B <ralf.bie...@gmail.com> wrote:
> I have a set of labels arranged along a timeframe in a. Each label has
> a timestamp and marks a state until the next label. The dataframe a
> contains 5 such timestamps and 5 associated labels. This means, on a
> continious scale between 1-100, there are 5 markers. E.g. 'abc' marks
> the timestampls between 10 and 19, 'def' marks the timestamps between
> 20 and 32, and so on.
>
> a <- data.frame(timestamp=c(3,5,8), mylabel=c("abc","def","ghi"))
> b <- data.frame(timestamp=c(1:10))
>
> I would like to assign these labels as an extra collumn 'label' to the
> data.frame b which currently only consists of a the timestamp. The
> output would then look like this:
>
> timestamp label
> 1 1 NA
> 2 2 NA
> 3 3 "abc"
> 4 4 "abc"
> 5 5 "def"
> 6 6 "def"
> 7 7 "def"
> 8 8 "ghi"
> 9 9 "ghi"
> 10 10 "ghi"
>
> What is the simplest way to assign these labels based on timestamps to
> get this output. The real dataset is several millions of rows...
>
> Thanks,
> Ralf
>
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
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