R help - Aug 2010 - Changing latitude data to decimal degrees

Hi All, 

I have location data set up as degrees: minutes: seconds (for example, 
122:45:45) I need to get this data into decimal degree form (eg, 122.7625). 

I know that I need to use the formula:

Decimal degrees = Degrees + (Minutes/60) + (Seconds/3600)

Does anyone know how I can get R to do this?
The original data is all in one column (called 'lat') and the degrees,
mins and
secs are divided by ':'
There are some values that are negative (eg -69:38:27), I think in these 
instances I need to do the calculation in the positive then multiply it by -1 to
make it negative again, the only problem is the positive and negative data are 
all intermingled, is there a way around this too?
I have R version 2.10.1 on a windows vista computer. 

I could do it manually but I have like 20,000 entries and would really like a 
little code to automate the conversion. 

I have tried Microsoft Access and Excel, but because the data is not stored in 
3 columns I cannot get it to work, I figured R was my best option but I cant get
it to work. It should be really simple but I'm new to R so would 
really appreciate help.

 Thank you for reading my plea, 
Please contact me if you need any more details
Any and all help is greatly appreciated,
sadz 



      
	[[alternative HTML version deleted]]

Tena koe Sadz

One way:

tt <- c('122:45:45','-69:38:27')
tt <- lapply(strsplit(tt,':'), as.numeric)
lapply(tt, function(x) x[1]+((x[1]>0)-0.5)*(x[2]+x[3]/60)/30)

To understand how this work you might need to break up the bits.

HTH ....

Peter Alspach
> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Sadz A
> Sent: Tuesday, 17 August 2010 11:43 a.m.
> To: r-help at r-project.org
> Subject: [R] Changing latitude data to decimal degrees
> 
> Hi All,
> 
> I have location data set up as degrees: minutes: seconds (for example,
> 122:45:45) I need to get this data into decimal degree form (eg,
> 122.7625).
> 
> I know that I need to use the formula:
> 
> Decimal degrees = Degrees + (Minutes/60) + (Seconds/3600)
> 
> Does anyone know how I can get R to do this?
> The original data is all in one column (called 'lat') and the
degrees,
> mins and
> secs are divided by ':'
> There are some values that are negative (eg -69:38:27), I think in
> these
> instances I need to do the calculation in the positive then multiply it
> by -1 to
> make it negative again, the only problem is the positive and negative
> data are
> all intermingled, is there a way around this too?
> I have R version 2.10.1 on a windows vista computer.
> 
> I could do it manually but I have like 20,000 entries and would really
> like a
> little code to automate the conversion.
> 
> I have tried Microsoft Access and Excel, but because the data is not
> stored in
> 3 columns I cannot get it to work, I figured R was my best option but I
> cant get
> it to work. It should be really simple but I'm new to R so would
> really appreciate help.
> 
>  Thank you for reading my plea,
> Please contact me if you need any more details
> Any and all help is greatly appreciated,
> sadz
> 
> 
> 
> 
> 	[[alternative HTML version deleted]]
> 
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