[R] julian day form POSIXt object

maxbre mbressan at arpa.veneto.it
Fri Sep 30 10:47:49 CEST 2011

here is an alternative long and winded solution to the problem sticking on
the julian function of chron package

test$year <- as.integer(as.character(test$date, "%Y"))
test$month <- as.integer(as.character(test$date, "%m"))
test$day <- as.integer(as.character(test$date, "%d"))
test$hour <- as.integer(as.character(test$date, "%H"))

test$jday <-julian(test$month,test$day,test$year,origin=c(month=1, day=0,

thank you all for helping me in sorting out the problem

by the way I like very much this very compact solution
test$doy <- as.POSIXlt(test$date)$yday+1
but on the other hand I'm still struggling to fully understand it,
especially for what is concerning the part after $: so what is $yday for?

if someone would be so kind to explain me this part I would be very grateful

a newbie in R
lesson learned


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