[GRASS-SVN] r71224 - in grass/branches/releasebranch_7_2: scripts/v.db.univar vector/v.univar

[svn_grass at osgeo.org]

Author: mlennert
Date: 2017-06-26 07:13:36 -0700 (Mon, 26 Jun 2017)
New Revision: 71224

Modified:
   grass/branches/releasebranch_7_2/scripts/v.db.univar/v.db.univar.html
   grass/branches/releasebranch_7_2/vector/v.univar/v.univar.html
Log:
v.univar/v.db.univar: update of manual to clarify difference (backport from trunk of r71207 - rr71211)


Modified: grass/branches/releasebranch_7_2/scripts/v.db.univar/v.db.univar.html
===================================================================
--- grass/branches/releasebranch_7_2/scripts/v.db.univar/v.db.univar.html	2017-06-26 13:54:33 UTC (rev 71223)
+++ grass/branches/releasebranch_7_2/scripts/v.db.univar/v.db.univar.html	2017-06-26 14:13:36 UTC (rev 71224)
@@ -3,9 +3,18 @@
 <em>v.db.univar</em> calculates basic univariate statistics for numeric
 attributes in a vector attribute table. It will calculate minimum, 
 maximum, range, mean, standard deviation, variance, coefficient of 
-variation, quartiles, median, and 90th percentile.
-It uses <em>db.select</em> to create list values for statistical calculations.
+variation, quartiles, median, and 90th percentile. 
 
+<p><em>v.db.univar</em> uses <em>db.univar</em> which in turn uses
+<em>db.select</em> to get the attribute values on which it calculates the
+statistics.  This means that statistics are calculated based on the entries in
+the attribute table, not based on the features in the map. One attribute value
+is read from each line in the attribute table, whether there are no, one or
+several features with the category value referenced by that line, or whether any
+features have more than one category value.  For feature-based, instead of
+attribute table-based, univariate statistics on attributes see <a
+href="v.univar.html">v.univar</a>.
+
 <em>NOTES</em>
 
 A database connection must be defined for the selected vector layer.

Modified: grass/branches/releasebranch_7_2/vector/v.univar/v.univar.html
===================================================================
--- grass/branches/releasebranch_7_2/vector/v.univar/v.univar.html	2017-06-26 13:54:33 UTC (rev 71223)
+++ grass/branches/releasebranch_7_2/vector/v.univar/v.univar.html	2017-06-26 14:13:36 UTC (rev 71224)
@@ -1,24 +1,34 @@
 <h2>DESCRIPTION</h2>
 
-<em>v.univar</em> calculates univariate statistics of vector map features.
-This includes the number of features counted, minimum, maximum values,
-and range. 
-Variance and standard deviation is calculated only for points if
-<b>type=point</b> is defined.
+<em>v.univar</em> calculates univariate statistics on (by default) an attribute
+of, or, through the <b>-d</b> flag on distance between, vector map features.
+Attributes are read per feature and per category value. This means that if the 
+map contains several features with the same category value, the attribute is 
+read as many times as there are features. On the other hand, if a feature has 
+more than one category value, each attribute value linked to each of the 
+category values of the feature is read. For statistics on one attribute 
+per category value, instead of one attribute per feature and per category,
+see <a href="v.db.univar.html">v.db.univar</a>.
 
 <p>Extended statistics (<b>-e</b>) adds median, 1st and 3rd quartiles, and 90th
 percentile to the output.
 
 <h2>NOTES</h2>
 
-When using the <b>-d</b> flag, univariate statistics of vector
-geometry are calculated. Depending on the selected vector <b>type</b>,
-distances are calculated as follows:
+When using the <b>-d</b> flag, univariate statistics of distances 
+between vector features are calculated. The distances from all features 
+to all other features are used. Since the distance from feature A to 
+feature B is the same like the distance from feature B to feature A, 
+that distance is considered only once, i.e. all pairwise distances 
+between features are used. Depending on the selected vector 
+<b>type</b>, distances are calculated as follows:
 
 <ul>
 <li> <b>type=point</b>: point distances are considered;</li>
-<li> <b>type=line</b>: the first point of each line is considered;</li>
-<li> <b>type=area</b>: the centroid of each area is considered.</li>
+<li> <b>type=line</b>: line to line distances are considered;</li>
+<li> <b>type=area</b>: not supported, use <b>type=centroid</b> instead (and see
+	<a href="v.distance.html">v.distance</a> for calculating distances
+	between areas)</li>
 </ul>
 
 <h2>EXAMPLE</h2>
@@ -116,6 +126,7 @@
 <a href="r.univar.html">r.univar</a>,
 <a href="v.db.univar.html">v.db.univar</a>,
 <a href="v.neighbors.html">v.neighbors</a>
+<a href="v.distance.html">v.distance</a>
 </em>