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

jcrosbie james at crosb.ie
Wed May 6 23:55:17 CEST 2015


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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