[MetaCRS] Specifying Coordinate Order in Test Data File...Again

[Martin Davis]

Landon,

I don't recall seeing this particular syntax before.  But the original 
discussion was a while ago, so probably I've just forgotten in the meantime.

I think it might be better to avoid "nested syntax" like this, since it 
does create parsing complexities (and may have an undesirable 
interaction with spreadsheet software, which I think was the original 
goal behind using CSV format). 

An alternative might be to have a single extra column which encodes the 
ordinate order as a simple string - eg. "XYZ".  There aren't that many 
reasonable orderings (possibly only 2 - XYZ and YXZ ?), so having a 
simple code seems sufficient.  And the code is easily extensible to 
other situations, and can be parsed if required.  (Wasn't there an issue 
with polar projections not fitting nicely in the XY model?)

Sunburned Surveyor wrote:
> Martin and I had a short discussion on the Proj4J mailing list about
> the need to specify the ordinate type in the metacrs test data file.
> It seems I added some test data northing first - easting second, which
> subsequently broke our code that parsed and executed the test data
> file. This backwards entry of coordinates comes from my background as
> a surveyor. That got Martin and I thinking it might be a good idea to
> reconsider introducing the ordinate type back into the the test data
> file. So instead of something like this:
>
> 2225563.01, 6352118.95, 10.21
>
> we would have something like this:
>
> y:2225563.01, x:6352118.95, z:10.21
>
> This change allows makes the format of the test data file a little
> looser by specifying the ordinate type with the ordinate value,
> instead of by convention in the order of the "columns" of the CSV
> file.
>
> What are the disadvantages of this approach? Does it allow us to code
> more robust test data file parsers? Does it make parsing more
> complicated?
>
> Are there any objections to this suggestion? Martin, did I communicate
> this idea correctly?
>
> Landon
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>   

-- 
Martin Davis
Senior Technical Architect
Refractions Research, Inc.
(250) 383-3022