[R] expand dataframe but time gap is not the same

Dagmar Ramgad82 at gmx.net
Thu Dec 3 11:51:56 CET 2015


Hello,
I hope someone can help me with my problem:
I have a dataframe like this:

datframe <- data.frame(dates=c("02.08.2013","03.08.2013","03.08.2013"), 
times =c("22:10","4:04", "10:18"), tide =c("NW","HW", "NW"))
datframe
Timestamp <- paste(datframe$dates, datframe$times)
myframe2 <- cbind( Timestamp,datframe)
head(myframe2)
myframe2$dates <- NULL
myframe2$times <- NULL
myframe2$Timestamp <- as.POSIXct (strptime(myframe2$Timestamp, "%d.%m.%Y 
%H:%M"), tz="GMT")
head(myframe2)
str(myframe2)

# In the end I want a frame like this:
datframeres <- data.frame(Timestamp=c("2013-08-02 22:10:00", "2013-08-02 
23:09:00","2013-08-03 00:08:00","2013-08-03 01:07:00", "2013-08-03 
02:06:00", "2013-08-03 03:05:00",
"2013-08-03 04:04:00","2013-08-03 05:06:20","2013-08-03 06:08:40", 
"2013-08-03 07:11:00", "2013-08-03 08:13:20", "2013-08-03 09:15:40", 
"2013-08-03 10:18:00")
, tidalclass =c("NW", "HW-5","HW-4", "HW-3", "HW-2", "HW-1", "HW", 
"HW+1","HW+2","HW+3", "HW+4","HW+5", "NW"))

datframeres

# That means: I want to expand to 13 classes instead of the two classes 
"HW" and "NW": "HW", "HW+1", "HW+2" and so on.
# The time gap between HW and NW is not always quite the same (always 
around 6 hours). So I would divide the time gap by 6 and add this number 
(0:59 and 1:02:20 respectively) to the timestamp before.
# I do not know how to do this. Does anyone know how to do this? Many 
thanks in advance!
Tagmarie



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