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

Frederic Ntirenganya ntfredo at gmail.com
Tue Nov 4 13:30:40 CET 2014

```Hi Daniel,

How can I add an if conditiopn or for loop to implement this in my
function?

ex: option1 : single date
option2: date in 3 columns (year,moth,day)

yday(Sys.Date())
yday(as.Date(paste(y,m,d,sep="-")))

Regards,
Frederic.

Frederic Ntirenganya
Maseno University,
African Maths Initiative,
Kenya.
Mobile:(+254)718492836
Email: fredo at aims.ac.za

On Tue, Nov 4, 2014 at 3:20 PM, daniel <daniel319 at gmail.com> wrote:

> 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
>>
>>         [[alternative HTML version deleted]]
>>
>> ______________________________________________
>> R-help at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
>
>
> --
> Daniel
>

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