.TH v.select 1grass "" "GRASS 6.4.4" "Grass User's Manual"
.SH NAME
\fI\fBv.select\fR\fR  - Selects features from vector map (A) by features from other vector map (B).
.SH KEYWORDS
vector, spatial query
.SH SYNOPSIS
\fBv.select\fR
.br
\fBv.select help\fR
.br
\fBv.select\fR [\-\fBtcr\fR] \fBainput\fR=\fIname\fR  [\fBatype\fR=\fIstring\fR[,\fIstring\fR,...]]   [\fBalayer\fR=\fIinteger\fR]  \fBbinput\fR=\fIname\fR  [\fBbtype\fR=\fIstring\fR[,\fIstring\fR,...]]   [\fBblayer\fR=\fIinteger\fR]  \fBoutput\fR=\fIname\fR  [\fBoperator\fR=\fIstring\fR]   [\fBrelate\fR=\fIstring\fR]   [\-\-\fBoverwrite\fR]  [\-\-\fBverbose\fR]  [\-\-\fBquiet\fR] 
.SS Flags:
.IP "\fB\-t\fR" 4m
.br
Do not create attribute table
.IP "\fB\-c\fR" 4m
.br
Do not skip features without category
.IP "\fB\-r\fR" 4m
.br
Reverse selection
.IP "\fB\-\-overwrite\fR" 4m
.br
Allow output files to overwrite existing files
.IP "\fB\-\-verbose\fR" 4m
.br
Verbose module output
.IP "\fB\-\-quiet\fR" 4m
.br
Quiet module output
.PP
.SS Parameters:
.IP "\fBainput\fR=\fIname\fR" 4m
.br
Name of input vector map (A)
.IP "\fBatype\fR=\fIstring[,\fIstring\fR,...]\fR" 4m
.br
Feature type (vector map A)
.br
Feature type
.br
Options: \fIpoint,line,boundary,centroid,area\fR
.br
Default: \fIpoint,line,boundary,centroid,area\fR
.IP "\fBalayer\fR=\fIinteger\fR" 4m
.br
Layer number (vector map A)
.br
A single vector map can be connected to multiple database tables. This number determines which table to use.
.br
Default: \fI1\fR
.IP "\fBbinput\fR=\fIname\fR" 4m
.br
Name of input vector map (B)
.IP "\fBbtype\fR=\fIstring[,\fIstring\fR,...]\fR" 4m
.br
Feature type (vector map B)
.br
Feature type
.br
Options: \fIpoint,line,boundary,centroid,area\fR
.br
Default: \fIpoint,line,boundary,centroid,area\fR
.IP "\fBblayer\fR=\fIinteger\fR" 4m
.br
Layer number (vector map B)
.br
A single vector map can be connected to multiple database tables. This number determines which table to use.
.br
Default: \fI1\fR
.IP "\fBoutput\fR=\fIname\fR" 4m
.br
Name for output vector map
.IP "\fBoperator\fR=\fIstring\fR" 4m
.br
Operator defines required relation between features
.br
A feature is written to output if the result of operation 'ainput operator binput' is true. An input feature is considered to be true, if category of given layer is defined.
.br
Options: \fIoverlap,equals,disjoint,intersects,touches,crosses,within,contains,overlaps,relate\fR
.br
Default: \fIoverlap\fR
.br
\fBoverlap\fR: features partially or completely overlap
.br
\fBequals\fR: features are spatially equals (using GEOS)
.br
\fBdisjoint\fR: features do not spatially intersect (using GEOS)
.br
\fBintersects\fR: features spatially intersect (using GEOS)
.br
\fBtouches\fR: features spatially touches (using GEOS)
.br
\fBcrosses\fR: features spatially crosses (using GEOS)
.br
\fBwithin\fR: feature A is completely inside feature B (using GEOS)
.br
\fBcontains\fR: feature B is completely inside feature A (using GEOS)
.br
\fBoverlaps\fR: features spatially overlap (using GEOS)
.br
\fBrelate\fR: feature A is spatially related to feature B (using GEOS, requires 'relate' option)
.IP "\fBrelate\fR=\fIstring\fR" 4m
.br
Intersection Matrix Pattern used for 'relate' operator
.PP
.SH DESCRIPTION
\fIv.select\fR allows the user to select features from a vector 
map by features from another one.
.PP
Supported operators (without GEOS):
.RS
.IP
\fBoverlap\fR - features partially or completely overlap
.RE
Supported operators (with GEOS):
.RS
.IP
\fBequals\fR - features are spatially equals
.IP
\fBdisjoint\fR - features do not spatially intersect
.IP
\fBintersects\fR - features spatially intersect
.IP
\fBtouches\fR - features spatially touches
.IP
\fBcrosses\fR - features spatially crosses
.IP
\fBwithin\fR - feature A is completely inside feature B
.IP
\fBcontains\fR - feature B is completely inside feature A
.IP
\fBoverlaps\fR - features spatially overlap
.IP
\fBrelate\fR - feature A is spatially related to feature B
.RE
.SH NOTES
Only features with category numbers will be considered. If required
the \fIv.category\fR module can be
used to add them. Typically boundaries do not need to be given a
category number, as an area's attributes are inherited from the
centroid. Typically points, lines, and centroids will always want to
have a cat number. E.g. take a road which separates two farms. It is
ambiguous as to which farm an attribute that is attached to the road
belongs to. The boundary only needs a cat number if it will hold its
own attributes, such as road name or pavement form. A centroid in each
paddock holds the information with respect to ownership, area, etc.
.SH EXAMPLES
Extract fire stations (points) from urban area map (polygon) - North Carolina
data set:
\fC
.DS
.br
v.select ainput=firestations binput=urbanarea output=urban_firestations \(rs
.br
         operator=overlap
.br
.DE
\fR
Extract Italian rivers from VMAP0 watercourses map:
\fC
.DS
.br
v.select ainput=watrcrsl_eurnasia_wgs84 binput=italy_area \(rs
.br
         output=watrcrsl_italy operator=overlap
.br
.DE
\fR
.SH TODO
Processing areas with GEOS is currently incredibly slow. Significant
speed-up is required.
.SH SEE ALSO
\fI
v.category,
v.overlay,
v.extract
\fR
.PP
GRASS SQL interface
.SH AUTHORS
Radim Blazek
.br
GEOS support by Martin Landa, Czech Technical University in Prague, Czech Republic
.PP
\fILast changed: $Date: 2012-12-10 11:32:07 +0100 (Mon, 10 Dec 2012) $\fR
.PP
Full index
.PP
© 2003-2014 GRASS Development Team