Hola Alberto,

en el siguiente link es posible que encuentres alguna clave para la 
solución: 
http://www.noamross.net/blog/2014/2/10/using-times-and-dates-in-r---presentation-code.html

Espero sea de utilidad.
Un saludo,

-- 

*Alexandre Alonso Fernández**
*Instituto de Investigaciones Marinas, IIM-CSIC
Departamento de Recursos y Ecología Marina
Grupo de Ecología Pesquera

<http://www.iim.csic.es/pesquerias>

El 09/07/2014 14:32, Carlos Ortega escribió:
> Hola,
>
> Obtienes un error por que no indicas el "origin", tal y como refleja
> fielmente la documentaciÃ³n:
>
>> as.Date(as.numeric(Sys.time()))Error in as.Date.numeric(as.numeric(Sys.time())) :
>    'origin' must be supplied
>
>
>
> ---------------------------------------------------------------------
> Details
>
> The usual vector re-cycling rules are applied to x and format so the answer
> will be of length that of the longer of the vectors.
>
> Locale-specific conversions to and from character strings are used where
> appropriate and available. This affects the names of the days and months.
>
> The as.Date methods accept character strings, factors, logical NA and
> objects of classes "POSIXlt
> <http://127.0.0.1:42870/help/library/base/help/POSIXlt>" and "POSIXct
> <http://127.0.0.1:42870/help/library/base/help/POSIXct>". (The last is
> converted to days by ignoring the time after midnight in the representation
> of the time in specified time zone, default UTC.) Also objects of class
> "date"(from package date
> <http://127.0.0.1:42870/help/library/date/html/as.date.html>) and "dates" (from
> package chron <http://127.0.0.1:42870/help/library/chron/html/chron.html>).
> Character strings are processed as far as necessary for the format
> specified: any trailing characters are ignored.
>
> *as.Date will accept numeric data (the number of days since an epoch),
> but only if origin is supplied.*
>
> The format and as.character methods ignore any fractional part of the date.
> ---------------------------------------------------------------------
>
> Saludos,
> Carlos Ortega
> www.qualityexcellence.es
>
>
>
>
>
> El 9 de julio de 2014, 14:25, Alberto Soria <alberto.soria@ari-solar.es>
> escribiÃ³:
>
>> Hola a todos:
>>
>> Debe de ser una tonterÃ­a, pero no consigo saber porque la siguiente linea
>> no devuelve la fecha actual:
>>
>> as.Date(as.numeric(Sys.time()))
>>
>> He hecho esa prueba porque no consigo pasar un numero convertido a partir
>> de una fecha y modificado a fecha de nuevo.
>>
>> Gracias por adelantado.
>>
>> Un saludo,
>> Alberto.
>>
>>          [[alternative HTML version deleted]]
>>
>>
>> _______________________________________________
>> R-help-es mailing list
>> R-help-es@r-project.org
>> https://stat.ethz.ch/mailman/listinfo/r-help-es
>>
>>
>
>
>
> _______________________________________________
> R-help-es mailing list
> R-help-es@r-project.org
> https://stat.ethz.ch/mailman/listinfo/r-help-es


<https://twitter.com/FisheriesIIM>

	[[alternative HTML version deleted]]

