[R] Dates - week and year not day.

[jim holtman]

Tack on a day of the week (6 as the last day) for a point of reference
for the conversion:

> dates <- paste('6.', 0:53, '.2011', sep = '')
> dates
 [1] "6.0.2011"  "6.1.2011"  "6.2.2011"  "6.3.2011"  "6.4.2011"
"6.5.2011"  "6.6.2011"
 [8] "6.7.2011"  "6.8.2011"  "6.9.2011"  "6.10.2011" "6.11.2011"
"6.12.2011" "6.13.2011"
[15] "6.14.2011" "6.15.2011" "6.16.2011" "6.17.2011" "6.18.2011"
"6.19.2011" "6.20.2011"
[22] "6.21.2011" "6.22.2011" "6.23.2011" "6.24.2011" "6.25.2011"
"6.26.2011" "6.27.2011"
[29] "6.28.2011" "6.29.2011" "6.30.2011" "6.31.2011" "6.32.2011"
"6.33.2011" "6.34.2011"
[36] "6.35.2011" "6.36.2011" "6.37.2011" "6.38.2011" "6.39.2011"
"6.40.2011" "6.41.2011"
[43] "6.42.2011" "6.43.2011" "6.44.2011" "6.45.2011" "6.46.2011"
"6.47.2011" "6.48.2011"
[50] "6.49.2011" "6.50.2011" "6.51.2011" "6.52.2011" "6.53.2011"
> as.POSIXct(dates, format = "%w.%W.%Y")
 [1] "2011-01-01 EST" "2011-01-08 EST" "2011-01-15 EST" "2011-01-22
EST" "2011-01-29 EST"
 [6] "2011-02-05 EST" "2011-02-12 EST" "2011-02-19 EST" "2011-02-26
EST" "2011-03-05 EST"
[11] "2011-03-12 EST" "2011-03-19 EDT" "2011-03-26 EDT" "2011-04-02
EDT" "2011-04-09 EDT"
[16] "2011-04-16 EDT" "2011-04-23 EDT" "2011-04-30 EDT" "2011-05-07
EDT" "2011-05-14 EDT"
[21] "2011-05-21 EDT" "2011-05-28 EDT" "2011-06-04 EDT" "2011-06-11
EDT" "2011-06-18 EDT"
[26] "2011-06-25 EDT" "2011-07-02 EDT" "2011-07-09 EDT" "2011-07-16
EDT" "2011-07-23 EDT"
[31] "2011-07-30 EDT" "2011-08-06 EDT" "2011-08-13 EDT" "2011-08-20
EDT" "2011-08-27 EDT"
[36] "2011-09-03 EDT" "2011-09-10 EDT" "2011-09-17 EDT" "2011-09-24
EDT" "2011-10-01 EDT"
[41] "2011-10-08 EDT" "2011-10-15 EDT" "2011-10-22 EDT" "2011-10-29
EDT" "2011-11-05 EDT"
[46] "2011-11-12 EST" "2011-11-19 EST" "2011-11-26 EST" "2011-12-03
EST" "2011-12-10 EST"
[51] "2011-12-17 EST" "2011-12-24 EST" "2011-12-31 EST" NA


On Tue, Aug 16, 2011 at 4:01 AM, holdnatalie <osp627 at bangor.ac.uk> wrote:
> Hi,
>
> I would be very grateful for some advice. I have read the help pages for
> Date, strptime, etc. All examples seem to use some version of day month year
> as date format. However I have Weekly composite data so ONLY want to input
> the dates as Week.Year (eg 35.2011). strptime seems to show this is possible
> using %W for week (UK convention) and %Y for year. My data is in a df called
> chlorophyll and has a date column. I tried to use the following (after I
> converted to characters using as.character);
>
> chlorophyll$date <- strptime("chlorophyll$date", "%W.%Y")
>
> It recognised the year but replaced the week part with todays date (16TH
> August).
>
> Any advice?
> Thanks
> Natalie
>
> --
> View this message in context: http://r.789695.n4.nabble.com/Dates-week-and-year-not-day-tp3746591p3746591.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>



-- 
Jim Holtman
Data Munger Guru

What is the problem that you are trying to solve?