error in seq.POSIXt?
Nothing jumps out at me, I'm sorry to say.
But in the meantime, I am wondering if it wouldn't be easier to
extract only the
winters with something like
datevec[format(datevec,'%m') %in% c('12','01','02') &
format(datevec,'%m-%d' != '02-29']
where datevec is the vector of days associated with your data, as an
object of class POSIXct or POSIXlt.
Then use something like
table(format(datevec,'%Y'))
to check that you have 90 of each.
-Don
At 3:27 PM -0600 5/31/02, Brandon Whitcher wrote:
I am trying to extract only the winters (defined to be 01-Dec through
28-Feb) of daily data from 1948-2002. There are 90 days in each winter
season. I wrote the following code to gather the winter dates into a
single vector:
DJF <- NULL
for(year in 1949:1999) {
temp.begin <- strptime(paste("01/12", year-1, sep="/"), "%d/%m/%Y")
temp.end <- strptime(paste("28/02", year, sep="/"), "%d/%m/%Y")
## Gives wrong answer:
temp.seq <- seq(temp.begin, temp.end, by="day")
if(is.null(DJF))
DJF <- temp.seq
else
DJF <- c(DJF, temp.seq)
cat("Winter:", year, "\t", length(temp.seq), "\n")
}
with the following output:
Winter: 1949 90
Winter: 1950 90
Winter: 1951 90
Winter: 1952 90
Winter: 1953 90
Winter: 1954 90
Winter: 1955 90
Winter: 1956 90
Winter: 1957 90
Winter: 1958 90
Winter: 1959 90
Winter: 1960 90
Winter: 1961 90
Winter: 1962 90
Winter: 1963 90
Winter: 1964 90
Winter: 1965 90
Winter: 1966 90
Winter: 1967 90
Winter: 1968 90
Winter: 1969 90
Winter: 1970 90
Winter: 1971 90
Winter: 1972 90
Winter: 1973 90
Winter: 1974 89
Winter: 1975 89
Winter: 1976 90
Winter: 1977 90
Winter: 1978 90
Winter: 1979 90
Winter: 1980 90
Winter: 1981 90
Winter: 1982 90
Winter: 1983 90
Winter: 1984 90
Winter: 1985 90
Winter: 1986 90
Winter: 1987 90
Winter: 1988 90
Winter: 1989 90
Winter: 1990 90
Winter: 1991 90
Winter: 1992 90
Winter: 1993 90
Winter: 1994 90
Winter: 1995 90
Winter: 1996 90
Winter: 1997 90
Winter: 1998 90
Winter: 1999 90
Winter: 2000 90
Winter: 2001 90
Winter: 2002 90
There are two years, 1974 and 1975, that produce only 89 days per winter.
I could not figure out what the cause of this was, but a workaround is two
rewrite the call to seq.POSIXt as:
temp.seq <- seq(temp.begin, length.out=90, by="day")
I am unsure why one works and one does not. Any ideas?
Brandon
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Geophysical Statistics Project
National Center for Atmospheric Research +1 303 497 1709 voice
P.O. Box 3000, Boulder, CO 80307-3000 +1 303 497 1333 fax
whitcher at ucar.edu www.cgd.ucar.edu/~whitcher/
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