Hi Ogbos, Remember that there is an underlying numeric representation of dates. as.Date assigns dates a number of days from an agreed origin (1970-01-01) while POSIX dates assign a number of seconds. If you plot in one system and then try to add points in another, it's not going to work. Jim
On Sun, Feb 17, 2019 at 12:55 PM Ogbos Okike <giftedlife2014 at gmail.com> wrote:
Dear Jim, Thank you and welcome back. It seems you have been away as you have not been responding to people's questions as before. I have just made a correction on my original question. Please have a look and check if I can still go the way u have suggested or if the correction would call for another approach. Best regards Ogbos On Sun, Feb 17, 2019, 02:22 Jim Lemon <drjimlemon at gmail.com> wrote:
Hi Ogbos,
It may be easier to use strptime:
dta<-data.frame(year=rep(2005,5),month=rep("05",5),
day=c("01","06","11","16","21"),
hour=c(2,4,6,8,10),minute=rep(0,5),second=rep(0,5),value=1:5)
dta$Ptime<-strptime(paste(paste(dta$year,dta$month,dta$day,sep="-"),
paste(dta$hour,dta$minute,dta$second,sep=":")),"%Y-%m-%d %H:%M:%S")
plot(dta$Ptime,dta$value)
text(strptime("2005-05-04 09:00:00","%Y-%m-%d %H:%M:%S"),4,"b")
Jim
On February 16, 2019 1:08:38 PM PST, Ogbos Okike <giftedlife2014 at gmail.com> wrote:
Dear Jeff,
One more problem please.
When I used as.Date(ISOdate(dta$year, dta$month, dta$day,dta$hour)) to
handle date, I could use text(as.Date("2005-03-13"),-9,"b") to label
my plot.
Now that I am using as.POSIXct(ISOdatetime(year,
month,day,hour,0,0))), can you please tell me how to text "b" on the
point corresponding with 1960-05-04 09:00:00 on my plot.
Many thanks for your extra time.
Best wishes
Ogbos