[R] subtracting degree minutes

[David L Carlson]

This probably doesn't count as simple, but you can convert your format, call it degrees.minutes, to decimal degrees, do the math and then convert back. The functions would be simple:

dm2dd <- function(x) trunc(x) + (x - trunc(x))/60*100
dd2dm <- function(x) trunc(x) + (x - trunc(x))*60/100

So your problem would be 

> dd2dm(dm2dd(44.1) - dm2dd(.2))
[1] 43.5

Of course you could wrap that into a function if you are planning to do it frequently.

-------------------------------------
David L Carlson
Department of Anthropology
Texas A&M University
College Station, TX 77840-4352

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of Trevor Davies
Sent: Thursday, June 26, 2014 2:43 PM
To: r-help at r-project.org
Subject: [R] subtracting degree minutes

Is there a simple way to subtract base-60 (coordinate system) values?

A trivial example:
I have a Lat of 44.1 degrees and I want to subtract 0.2 degrees from it.
 Therefore the answer should be 43.5 degrees (base 60).

I can do a change to character; stringsplit ; change back - deal with the
leading zeros but there must be an easier way.  (?)

Thanks for the help.
Trevor

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