[R] Alternative to extended recode sintax? Bug?

[David Winsemius]

On Dec 20, 2010, at 10:58 AM, Luca Meyer wrote:

> Right, I appreciate the first day of the year start date. I am just  
> wondering why then the cut off day is not the same for the rest of  
> the year...but it's all right to use other packages.

Are you saying it shifts within the year? I am not seeing that:

require(lubridate)

 > weekdays(as.POSIXct("2010-01-01")+(0:8)*24*60*60)
[1] "Friday"    "Saturday"  "Sunday"    "Monday"    "Tuesday"    
"Wednesday"
[7] "Thursday"  "Friday"    "Saturday"
 > week(as.POSIXct("2010-01-01")+(0:8)*24*60*60)
[1] 1 1 1 1 1 1 2 2 2

Looks to be incrementing weeks between Wed and Thurs at the beginning  
of the year just as it did in your example. I admit that I thought  
that it should be shifting at the Thursday - Friday divide, but  
setting a zero point can be ambiguous. I thought if it were  Midnight  
Thursday-Friday that all of Thurdays would be in week 1. But at least  
it appears consistent.


> Thanks,
> Luca
>
> Il giorno 20/dic/2010, alle ore 14.16, David Winsemius ha scritto:
>
>>
>> On Dec 20, 2010, at 12:54 AM, Luca Meyer wrote:
>>
>>> All right, I get it now: lubridate's week() define weeks from  
>>> Thursday till the following Wednesday. You'd probably agree with  
>>> me that it's a bit strange what it is going to do over the turn of  
>>> the year:
>>>
>>>> y <-  
>>>> as.POSIXct(c("2010-12-27","2010-12-28","2010-12-29","2010-12-30","2010-12-31","2011-01-01","2011-01-02","2011-01-03","2011-01-04","2011-01-05","2011-01-06","2011-01-07","2011-01-08","2011-01-09","2011-01-10","2011-01-11","2010-01-12","2010-01-13","2010-01-14"))
>>>> week(y)
>>> [1] 52 52 52 53 53  1  1  1  1  1  1  2  2  2  2  2  2  2  3
>>>
>>> Why would the first week of the year be made of 6 days and the  
>>> turn from week 1 to week 2 on the night between Thursday and  
>>> Friday and not Wednesday and Friday like every other week?
>>
>> weeks in lubridate start on whatever day of the week is the first  
>> of that year.
>>
>> If you want a Monday starting day (or the option to change to  
>> another starting day), then package chron has such facilities.
>>
>>
>>>
>>> Cheers,
>>> Luca
>>>
>>>
>>>
>>> Il giorno 19/dic/2010, alle ore 18.14, Uwe Ligges ha scritto:
>>>
>>>>
>>>>
>>>> On 19.12.2010 13:20, David Winsemius wrote:
>>>>>
>>>>> On Dec 19, 2010, at 5:11 AM, Luca Meyer wrote:
>>>>>
>>>>>> Something goes wrong with the week function of the lubridate  
>>>>>> package:
>>>>>>
>>>>>>> x= as.POSIXct(factor(c("2010-12-15 17:28:27",
>>>>>> + "2010-12-15 17:32:34",
>>>>>> + "2010-12-15 18:48:39",
>>>>>> + "2010-12-15 19:25:00",
>>>>>> + "2010-12-16 08:00:00",
>>>>>> + "2010-12-16 08:25:49",
>>>>>> + "2010-12-16 09:00:00")))
>>>>>>> require(lubridate)
>>>>>
>>>>>>> weekdays(x)
>>>>>> [1] "Mercoledì" "Mercoledì" "Mercoledì" "Mercoledì" "Giovedì"
>>>>>> "Giovedì" "Giovedì"
>>>>>>> week(x)
>>>>>> [1] 50 50 50 50 51 51 51
>>>>>
>>>>> But 2010-12-15 is a Wednesday and 2010-12-16 is a Thursday.
>>>>>
>>>>
>>>>
>>>> Together with the description of ?week this shows that  
>>>> lubridate's week() function works as documented rather than as  
>>>> expected by Luca Meyer.
>>>>
>>>> Uwe Ligges
>>>
>>
>> David Winsemius, MD
>> West Hartford, CT
>>
>

David Winsemius, MD
West Hartford, CT