[GRASS5] readsites() TODO list...

[Bill Brown - staff]

>
>Here's the deal.  I just picked this up, cause I saw it on the TODO list
>on the website(s).  Anyway, I've coded this thing up, tested it, and it
>works as planned.  The question of course, is this functionality worthy
>of a library function?  I will have to concede, I think it isn't.  I
>guessed that there must've been a significant demand for this limited
>function, but perhaps the more general is desirable. 

I think your G_readxyzsites would be quite useful.  I'd still like to
see "cat" added as an attribute, though.  G_writexyzsites might be good
too.  I think these would be more useful to the programmer because it 
hides all the messy Site structure stuff. For G_writexyzsites, if "cat"
is selected, you could default to writing a double cat or add another
RASTER_MAP_TYPE parameter which would be ignored if string or floating
point attribute are chosen.

>int    type,    /* 0 = Z-dim, 1 = double, 2 = string */
>	
>--- This is the attribute type. By "Z-dim", I mean any of the n-dims
>--- in the Site file spec. Double, is double attribute, string is
>--- string attribute.  Yes, an enum or #define's are in order.

Z-dim is still confusing to me.  Maybe I'm just being dense.  So is
Z-dim 1 the same as easting and Z-dim 2 the same as northing?  If so,
let's just call it "dim" - if not, "n-dim" might be better.  When I
wrote d.sites.qual, I considered dim 1 to be the same as easting.
( http://www2.gis.uiuc.edu:2280/modviz/gsoils/doc/dsites_qual.html )
Here's a chunk from the Sites Format Specification:
------------------------
Part 1 of a Site Record: Location

Part 1 of a site record gives information about location. The
field separator in part 1 of the site record is a "pipe" (ASCII
0x7c) character. The last (non-escaped) pipe signifies the end
of part 1 (an escaped character is defined as one prefixed by a
"backslash" (ASCII 0x5c)). Any additional fields are
considered attribute information. 

Each field in part 1 indicates a coordinate in some space.
There must be at least two fields in part 1: the first describing
a geographic easting and the second describing a geographic
northing. These may be in either decimal or
degrees-minutes-second format. 

Additional fields in part 1 are optional but must be stored in
decimal format. They should only be used to represent
coordinate information about some space (e.g., elevation,
time; depending upon how a space is defined). 
------------------------

>
>Anyway, shall I look at writing a generalized G_readsites() (and maybe
>G_writesites() ?) using the standard Site struct?  I'm ambivalent.
>

Me too.  I'd consider these "convenience" functions. 

Thanks!

- Bill


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