[R] number of Mondays

[Carlos Hernandez]

Indeed, i overlooked weekdays.

Thank you all for your replies!


On Jan 15, 2009, at 21:23 , Prof Brian Ripley wrote:

> Or for those not allergic to reading help, see ?weekdays .
>
> Just how hard do you have to work to miss that?  E.g. ??day works.
>
> On Thu, 15 Jan 2009, Peter Dalgaard wrote:
>
>> Carlos Hernandez wrote:
>>> dear All,
>>> i'm trying to calculate the number of Mondays, Tuesdays, etc that  
>>> each
>>> month within a date range has. I have time series data that spans 60
>>> months and i want to calculate the number of Mondays, Tuesdays,  
>>> Wed, etc
>>> of each month. (I want to control for weekly seasonality but my  
>>> data is
>>> monthly).
>>>
>>> Is there an easy way to to this in R? or is there a package i  
>>> could use?
>>> i did some quick search in the help files and R sites but could  
>>> not find
>>> any answers.
>>>
>>> i appreciate any hint you could give,
>>
>> This is where POSIXlt objects are useful:
>>
>>> unlist(unclass(as.POSIXlt(ISOdate(1959,3,11))))
>> sec   min  hour  mday   mon  year  wday  yday isdst
>>   0     0    12    11     2    59     3    69     0
>>
>> Which means that I was born on a Wednesday (wday==3) in March  
>> (mon==2)
>> (some of the fields count from 0 and others, like mday, from 1;
>> presumably some UNIX vendor back in the Stone Age got their
>> implementation turned into a standard...).
>>
>> This allows you to do stuff like:
>>
>>
>>> dd <- seq(Sys.Date(),as.Date("2009-3-11"),1)
>>> dd <- as.POSIXlt(dd)
>>> with(dd, table(mon,wday))
>>  wday
>> mon 0 1 2 3 4 5 6
>> 0 2 2 2 2 3 3 3
>> 1 4 4 4 4 4 4 4
>> 2 2 2 2 2 1 1 1
>>
>> which I think is pretty much what you were looking for.
>>
>>
>>> thanks.
>>>
>>> Carlos
>>>
>>> ______________________________________________
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>>> PLEASE do read the posting guide
>>> http://www.R-project.org/posting-guide.html
>>> and provide commented, minimal, self-contained, reproducible code.
>>
>>
>> --
>>  O__  ---- Peter Dalgaard             Øster Farimagsgade 5, Entr.B
>> c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
>> (*) \(*) -- University of Copenhagen   Denmark      Ph:  (+45)  
>> 35327918
>> ~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)              FAX: (+45)  
>> 35327907
>>
>> ______________________________________________
>> 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.
>>
>
> -- 
> Brian D. Ripley,                  ripley at stats.ox.ac.uk
> Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
> University of Oxford,             Tel:  +44 1865 272861 (self)
> 1 South Parks Road,                     +44 1865 272866 (PA)
> Oxford OX1 3TG, UK                Fax:  +44 1865 272595