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daylight

bambus
hi there,
does anyone know how to calculate the amount of daylight on every day of the year in R? I mean the time between sunrise and sunset.

thanks
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Re: daylight

Mark Dalphin-2
I would start with the data. My source for this is the US Navy
Sunrise/Sunset tables:
    http://aa.usno.navy.mil/data/docs/RS_OneYear.php

The page is produces is pure text; I've previously extracted the values
with a simple Perl script, but would do it today using R (in general,
most of the parsing I used to perform in Perl can readily be performed
in R).

Once I had the data available as a data frame, I'd convert the columns
to POSIXct format and then use difftime().

Cheers,
Mark

bambus wrote:

> hi there,
> does anyone know how to calculate the amount of daylight on every day of the
> year in R? I mean the time between sunrise and sunset.
>
> thanks
>
>
>
> --
> View this message in context: http://r.789695.n4.nabble.com/daylight-tp4647213.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> [hidden email] 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.
>  
--
       


    Mark Dalphin Ph.D.

Director of Bioinformatics

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*Ph:* +64-3-479-5805
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Re: daylight

David Winsemius
In reply to this post by bambus

On Oct 23, 2012, at 12:45 PM, bambus wrote:

> hi there,
> does anyone know how to calculate the amount of daylight on every day of the
> year in R? I mean the time between sunrise and sunset.

http://www.esrl.noaa.gov/gmd/grad/solcalc/sunrise.html

This should explain why you are posing an underdetermined problem.

--
>
> View this message in context: http://r.789695.n4.nabble.com/daylight-tp4647213.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> [hidden email] 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.

David Winsemius, MD
Alameda, CA, USA

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Re: daylight

Jeff Newmiller
In reply to this post by bambus
library(maptools)
?sunriset
---------------------------------------------------------------------------
Jeff Newmiller                        The     .....       .....  Go Live...
DCN:<[hidden email]>        Basics: ##.#.       ##.#.  Live Go...
                                      Live:   OO#.. Dead: OO#..  Playing
Research Engineer (Solar/Batteries            O.O#.       #.O#.  with
/Software/Embedded Controllers)               .OO#.       .OO#.  rocks...1k
---------------------------------------------------------------------------
Sent from my phone. Please excuse my brevity.

bambus <[hidden email]> wrote:

>hi there,
>does anyone know how to calculate the amount of daylight on every day
>of the
>year in R? I mean the time between sunrise and sunset.
>
>thanks
>
>
>
>--
>View this message in context:
>http://r.789695.n4.nabble.com/daylight-tp4647213.html
>Sent from the R help mailing list archive at Nabble.com.
>
>______________________________________________
>[hidden email] 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.

______________________________________________
[hidden email] 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.
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Re: daylight

glsnow
In reply to this post by bambus
Do you care about local topography/terrain?  I think most of the
calculators/tables that are commonly used assume that you are at a
fairly flat place on the earth's surface, but that is not always true.
 The area where my wife grew up had its longest day closer to the
equinox than the summer solstice and if I wanted to calculate the
number of hours that direct sunlight would hit solar panels (which I
don't have yet) on my house or the solar oven (which I do have) in my
back yard, then assuming sunset and sunrise occurred at 90 degrees
from vertical would definitely overestimate the time.

On Tue, Oct 23, 2012 at 1:45 PM, bambus <[hidden email]> wrote:

> hi there,
> does anyone know how to calculate the amount of daylight on every day of the
> year in R? I mean the time between sunrise and sunset.
>
> thanks
>
>
>
> --
> View this message in context: http://r.789695.n4.nabble.com/daylight-tp4647213.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> [hidden email] 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.



--
Gregory (Greg) L. Snow Ph.D.
[hidden email]

______________________________________________
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