On Oct 20, 2010, at 11:47 AM, Sadz A wrote:
Hi,
I am trying to do some calculations turning DMS data to decimal
degrees using
the formula (D+(M/60)+(S/3600)), some of the D's involve -ve
numbers, the
easiest way to do the calculation is to use absolute numbers then
use the 'sign'
function in R to change the answer back to the correct -ve or +ve,
for example, if;
D<--69
M<-8
S<-10
then
decimal<-D+(M/60)+(S/3600)
-69+(8/60)+(10/3600) = this would equal -68.86389 (which is
wrong, it should
be -69.13611, so i used the following function)
decimal<-(abs(D)+(M/60)+(S/3600))
decimal.degs<-sign(D)*decimal
decimal.degs
-69.13611
because ((69+(8/60)+(10/3600)=69.13611) and then the -sign is put
back in.
This works fine untill D=0
because then 'sign' does not give 0 a +ve sign it takes it as 0 and
multiplies
decimal by 0 to give 0.
example
D<-0
decimal<-D+(M/60)+(S/3600)
decimal.degs<-sign(D)*decimal
decimal.degs
0
Is there anyway to get around this??????????
I am not sure I understand the source of your distress. Why are you
disturbed that 0 returns 0? ??????
and make D=0 a positive and not a 0 with sign or another
function??????
You can always define your own function:
nonneg <- function(x) { 0 + !sign(x) }
> nonneg(0)
[1] 1
Any help is appreciated
Thank you
sadz
ps please email me if you need more info
--
David Winsemius, MD
West Hartford, CT
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