KEYWORDS

vector, database, attribute table

SYNOPSIS

v.vect.stats

v.vect.stats help

v.vect.stats [-p] points=name areas=name [type=string[,string,...]] [player=integer] [alayer=integer] [method=string] [pcolumn=name] [ccolumn=string] [scolumn=string] [fs=character|space|tab] [--verbose] [--quiet]

Flags:

-p

Print output to stdout, do not update attribute table

First column is always area category

--verbose

Verbose module output

--quiet

Quiet module output

Parameters:

points=name

Name of existing vector map with points

areas=name

Name of existing vector map with areas

type=string[,string,...]

Feature type

Feature type

Options: point,centroid

Default: point

player=integer

Layer number for points map

A single vector map can be connected to multiple database tables. This number determines which table to use.

Default: 1

alayer=integer

Layer number for area map

A single vector map can be connected to multiple database tables. This number determines which table to use.

Default: 1

method=string

Method for aggregate statistics

Options: sum,average,median,mode,minimum,min_cat,maximum,max_cat,range,stddev,variance,diversity

pcolumn=name

Column name of points map to use for statistics

Column of points map must be numeric

ccolumn=string

Column name to upload points count

Column to hold points count, must be of type integer, will be created if not existing

scolumn=string

Column name to upload statistics

Column to hold statistics, must be of type double, will be created if not existing

fs=character|space|tab

Field separator

Output field separator

Default: |

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.

RELATED TO v.vect.stats…

v.distance, r.distance, v.what.vect

AUTHOR

Markus Metz

Last changed: $Date: 2008-08-13 21:52:37 +0200 (Wed, 13 Aug 2008) $

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