DESCRIPTION
v.vect.stats counts the number of points in vector map
points falling into each area in vector map areas.
Optionally statistics on point attributes in points are
calculated for each area. The results are either uploaded to the
attribute table of the vector map areas or printed to stdout.
OPTIONS
Statistical Methods:
Using numeric attribute values of all points falling into a given area,
a new value is detmined with the selected method.
v.vect.stats can perform the following operations:
- sum
- The sum of values.
- average
- The average value of all point attributes (sum / count).
- median
- The value found half-way through a list of the
attribute values, when these are ranged in numerical order.
- mode
- The most frequently occurring value.
- minimum
- The minimum observed value.
- min_cat
- The point category corresponding to the minimum observed value.
- maximum
- The maximum observed value.
- max_cat
- The point category corresponding to the maximum observed value.
- range
- The range of the observed values.
- stddev
- The statistical standard deviation of the attribute values.
- variance
- The statistical variance of the attribute values.
- diversity
- The number of different attribute values.
NOTES
Points not falling into any area are ignored. Areas without category
(no centroid attached or centroid without category) are ignored.
If no points are falling into a given area, the point count is set to 0
(zero) and the statistics result to "null".
The columns count_column and stats_column are created if not
existing. If they do already exist, the count_column must be of
type integer and the stats_column of type double.
SEE ALSO
v.distance,
r.distance,
v.what.vect
AUTHOR
Markus Metz
Last changed: $Date: 2008-08-13 21:52:37 +0200 (Wed, 13 Aug 2008) $