[R] How to finding a given length of runs in a series of data?

[Adams, Jean]

Two libraries are needed to run the code you submitted ...

library(dplyr)
library(sqldf)

Your IsHigh() function and its use can be replaced by a single line of code

isHighFlow <- as.numeric(Flow>=1600)

You are getting the additional hour by using cumsum().  One date element
which you seem to characterize as zero hours returns a one in cumsum, two
returns two, etc.
cumsum(c(1, 0, 1, 1, 0, 1, 1, 1, 0))

If everything is off by one hour, just subtract a 1.  Problem solved.

Jean


On Wed, May 6, 2015 at 5:55 PM, jcrosbie <james at crosb.ie> wrote:

> I'm trying to study times in which flow was operating at a given level or
> greater. To do so I have created a way to see how long the series has
> operated at a high level. But for some reason the data is calculating the
> runs one hour to long. Any ideas on why?
>
>
>
>
>
> Code:
> Date<-format(seq(as.POSIXct("2014-01-01 01:00"), as.POSIXct("2015-01-01
> 00:00"),     by="hour"), "%Y-%m-%d %H:%M", usetz = FALSE)
> Flow<-runif(8760, 0, 2300)
>
> IsHigh<- function(x ){
>     if (x < 1600) return(0)
>     if (1600 <= x) return(1)
> }
>
> isHighFlow = unlist(lapply(Flow, IsHigh))
>
> df = data.frame(Date, Flow, isHighFlow )
>
>
> temp <- df %>%
>   mutate(highFlowInterval = cumsum(isHighFlow==0)) %>%
>   group_by(highFlowInterval) %>%
>   summarise(hoursHighFlow = n(), minDate = min(as.character(Date)), maxDate
> = max(as.character(Date)))
>
> #Then join the two tables together.
> temp2<-sqldf("SELECT *
>   FROM temp LEFT JOIN df
>   ON df.Date BETWEEN temp.minDate AND temp.maxDate")
>
>
>
> --
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> Sent from the R help mailing list archive at Nabble.com.
>
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