On Sep 15, 2010, at 12:05 PM, Sean Parks wrote:
Hi,
I'm attempting to add a "Julian Day" column to a data frame.
Here is my code and the resulting data frame:
vic.data <- read.table("C:/VIC/data/vic.data.csv", header=F)
names(vic.data) <- c("year", "month", "day", "precip", "evap",
"runoff", "baseflow", "Tsup", "SM1", "SM2", "SM3", "SWE")
vic.data$julian.day <- julian(vic.data$temp.date, origin =
as.Date("1900-01-01"))[1]
There's one problem. Why are you appending the "[1]? to the as.Date
function. It's just going to give you the first date.
--
David.
head(vic.data)
year month day precip evap runoff baseflow Tsup SM1 SM2
SM3 SWE temp.date julian.day
1 1916 1 1 0.00 0.0789 0 0.5037 -15.9907 20.2285
63.4011
296.9437 214.7537 1916-01-01 5843
2 1916 1 2 0.00 0.1135 0 0.5030 -14.1946 20.1619
63.3425
296.5659 214.7009 1916-01-02 5843
3 1916 1 3 29.74 0.1584 0 0.5024 -11.1894 20.0998
63.2817
296.1864 244.0971 1916-01-03 5843
4 1916 1 4 11.37 0.2056 0 0.5017 -12.9745 20.0416
63.2194
295.8052 255.3145 1916-01-04 5843
5 1916 1 5 0.00 0.1467 0 0.5011 -15.1542 19.9866
63.1561
295.4224 255.2361 1916-01-05 5843
6 1916 1 6 0.00 0.0939 0 0.5004 -12.5409 19.9345
63.0922
295.0379 255.2084 1916-01-06 5843
As you can see, the "temp.date" column behaves as expected, but the
"julian.day" column is populated with the Julian day value from
1/1/1916.
Please help me out if you have some ideas.
Thanks,
Sean
*************************
Sean Parks
Ecologist | Geospatial Analyst
Aldo Leopold Wilderness Research Institute
Rocky Mountain Research Station
(406) 542-4182
http://leopold.wilderness.net/
*************************
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