[R-sig-Geo] Figuring out a locations local daylight hours

[Ben]

the maptools library in R can take care of this easily. Look for the 
sunriset function. You can get hours of daylight based on times of 
sunrise and sunset, and adjust according to whatever type of twilight 
definition you wish (i.e. civil vs. astronomical)

hope that helps

Ben

------ Original Message ------
From: "steven brey" <fierceturtle at gmail.com>
To: r-sig-geo at r-project.org
Sent: 5/20/2014 3:19:23 PM
Subject: [R-sig-Geo] Figuring out a locations local daylight hours

>I am using R to write a text forecast for particulate matter
>concentrations. Given a date, latitude, and longitude I would like to
>figure out the local daylight hours. Does anyone know of a resource
>that can make this calculation? I wanted to see if there was an
>existing resource/solution before diving into the
>trigonometry/astronomy 101 necessary to figure this out.
>
>Cheers
>
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