[R] Function that create day of the year column.

[daniel]

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 <ntfredo at 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: fredo at aims.ac.za
> https://sites.google.com/a/aims.ac.za/fredo/
>
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>
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>



-- 
Daniel

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