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@@ -1,31 +1,36 @@
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<h2>DESCRIPTION</h2>
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-<em>v.what.vect</em> transfers attributes from the <b>query_map</b>'s map
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-attribute table into the attribute table of <u>points</u> present in the
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-<b>map</b> map. The script is based on <em>v.distance</em>.
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+<em>v.what.vect</em> transfers attributes from the <b>query_map</b>'s
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+attribute table into the <b>map</b>'s attribute table. The module can
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+be used to transfer attributes from the table of a polygon map into the
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+attribute table of a point vector map, as well as the other way around,
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+i.e., from a point map into the attribute table of a polygon map (See
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+examples). The script is based on <em>v.distance</em>.
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<h2>NOTES</h2>
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-The upload <b>column</b>, into which the query results are stored, must be
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-present in the <b>map</b> map. Use <em>v.db.addcolumn</em> to add one if needed.
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-<p>Use dmax parameter to control query distance tolerance (how far points/centroids
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-can be from <b>query_map</b> features). For more options, use
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-<em>v.distance</em> instead.
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-<p>In case of a multipoint input <b>map</b> map, with several points having the
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-same category number, it can happen, that the query result is NULL, if the same
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+The upload <b>column</b> into which the query results are stored must be
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+present in <b>map</b>. Use <em>v.db.addcolumn</em> to add one if needed.
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+<p>Use the <b>dmax</b> parameter to control the query distance tolerance, i.e.,
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+how far <b>map</b>'s points/centroids can be from the <b>query_map</b> features.
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+For further options, use <em>v.distance</em>.
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+<p>In case of a multipoint input <b>map</b> with several points having the
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+same category number, it can happen that the query result is NULL if the same
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category number falls into different <b>query_map</b> polygons.
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-<p>When transferring attributes from a point map to a polygon map, usually <b>dmax</b>
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-has to be larger than zero (determined by distance between query points and
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-polygon centroids).
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-<p>In case that one or both input vector maps are 3D, features need to touch also
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-in the 3rd dimension (z coordinate) in order to transfer attributes.
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+<p>When transferring attributes from a point map into a polygon map,
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+<b>dmax</b> has to be larger than zero, i.e., it will be determined by the
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+distance between query points and polygon centroids. Importantly, distance
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+is in meters for latitude-longitude locations.
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+<p>In case that one or both input vector maps are 3D, features need to
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+touch also in the 3rd dimension (z coordinate) in order to transfer
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+attributes.
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<h2>EXAMPLES</h2>
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In this example, the 'hospitals' point map in the North Carolina location is
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copied to the current mapset, a new attribute column is added and the urban
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-names from the 'urbanarea' polygon map are transferred to the 'myhospitals'
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-map at the hospital points' locations:
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+names from the 'urbanarea' polygon map are transferred to hospital points
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+locations in 'myhospitals' map:
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<div class="code"><pre>
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g.copy vect=hospitals,myhospitals
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@@ -35,12 +40,12 @@ v.what.vect myhospitals query_map=urbanarea column=urb_name query_column=NAME
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v.db.select myhospitals
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</pre></div>
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<p>
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-In this example, city names, population data and more from
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+In this example, city names, population data and others from
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<a href="http://download.geonames.org/export/dump/">Geonames.org country files</a> are
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transferred to selected EU CORINE landuse/landcover classes
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("Continuous urban fabric", 111, and "Discontinuous urban fabric", 112).
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-Note: Example in UTM projection to which the input maps have been projected
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-beforehand to have metric distances support:
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+Note: The example is in UTM projection to which the input maps have been
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+projected beforehand.
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<div class="code"><pre>
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# extract populated places from geonames
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@@ -51,7 +56,7 @@ v.db.addcol corine_code111_112_cities column="gnameid double precision"
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v.what.vect corine_code111_112_cities query_map=geonames_IT_cities column=gnameid \
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query_column=geonameid dmax=3000
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# now gnameid can be used for v.db.join to join further
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-# attributes in from geonames.org
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+# attributes from geonames.org
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</pre></div>
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<h2>SEE ALSO</h2>
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Veronica Andreo