[R-sig-Geo] Re-scale units of coordinates in sf geometry?

[Edzer Pebesma]

On 25/01/2023 18:42, Josiah Parry wrote:
> I wonder if `units::set_units()` is a better fit for the job
> https://r-quantities.github.io/units/articles/measurement_units_in_R.html

It could definitely tell you which number to choose when going from, 
say, US feet to km. Coordinates in sf geometries are not stored as units 
objects, unit info is encoded in the CRS. st_transform can do 
transformations and conversions between different CRSs, unit conversions 
is a special case of that.

> 
> On Wed, Jan 25, 2023 at 12:37 PM Steve Gutreuter <sgutreuter using gmail.com>
> wrote:
> 
>> Is it safe to re-scale sf geometry coordinates from meters to
>> kilometers using, for example:
>>
>> sfobj$geometry <- sfobj$geometry / 1000
>>
>> It seems to work, but I understand too little about spatial data to
>> know whether that practice is actually safe.  I am working with spatial
>> data in a continental-scale equidistant conic projection, and the units
>> are meters.  It seems that kilometers would be better suited stochastic
>> partial differential equation modeling on a finite-element mesh, but
>> maybe that is a moot point.
>>
>> Any and all advice will be much appreciated.
>>
>> Thanks!
>> --
>> Steve Gutreuter
>>
>>          [[alternative HTML version deleted]]
>>
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-- 
Edzer Pebesma
Institute for Geoinformatics
Heisenbergstrasse 2, 48151 Muenster, Germany
Phone: +49 251 8333081