Frederic,
Check the lubridate library.
install.packages("lubridate")
library(lubridate)
yday(Sys.Date())
d <- 4
m <- 11
y <- 2014
yday(as.Date(paste(y,m,d,sep="-")))
Daniel Merino
2014-11-04 7:01 GMT-03:00 Frederic Ntirenganya <ntfr...@gmail.com>:
> Dear All,
>
> I would like to make a function that create Day of the year column in a
> dataset.
> State of the problem: write a function that create a day column either from
> a single date column (string/or factors) or from date in 3 columns (year,
> month, day).
>
> I made the following function for a single date. I would like to add a
> condition for date in 3 columns (year, month, day). My data is daily
> climate data.
> #write a function that create a day column either from a single date column
> (string/or factors)
> #or from date in 3 columns (year, month, day).
>
> DOY=function(data){
>
> #=================================================================
> #This function create day of teh year from a single date
> column(ex:2009-08-02) or/and
> #from the date in 3 columns (Year, month, Day).
> #================================================================
> data$Rain=as.numeric(as.character(data$Rain))
> dt=yday(data$Date) # single date of the data
> datelp= dt>59 & !leap_year(data$Date)# tell us that the date occurs
> during a leap year
> dt[datelp]=dt[datelp]+1 # add one for non leap_year
> cbind(data, dt) # combining columns of data
> conames(data)="DOY" # name of new column. ??I have a problem on how I can
> precise the column in gerenal.
> }
>
> ex: year month day Date Rain Tmin Tmax
> 1971 1 1 1971-01-01 0 8.2 15
> 1971 1 2 1971-01-02 0 4.2 11
> . . . . . . .
> . . . . . . .
> . . . . . . .
>
> Any ideal on how I can make this function is welcome. thanks!
> Frederic Ntirenganya
> Maseno University,
> African Maths Initiative,
> Kenya.
> Mobile:(+254)718492836
> Email: fr...@aims.ac.za
> https://sites.google.com/a/aims.ac.za/fredo/
>
> [[alternative HTML version deleted]]
>
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>
--
Daniel
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