.TH v.patch 1grass "" "GRASS 6.4.2" "Grass User's Manual"
.SH NAME
\fI\fBv.patch\fR\fR  - Create a new vector map layer by combining other vector map layers.
.SH KEYWORDS
vector, geometry
.SH SYNOPSIS
\fBv.patch\fR
.br
\fBv.patch help\fR
.br
\fBv.patch\fR [-\fBae\fR] \fBinput\fR=\fIname\fR[,\fIname\fR,...] \fBoutput\fR=\fIname\fR  [\fBbbox\fR=\fIname\fR]   [--\fBoverwrite\fR]  [--\fBverbose\fR]  [--\fBquiet\fR] 
.SS Flags:
.IP "\fB-a\fR" 4m
.br
Append files to existing file (overwriting existing files must be activated)
.IP "\fB-e\fR" 4m
.br
Copy also attribute table
.br
Only the table of layer 1 is currently supported
.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 "\fBinput\fR=\fIname[,\fIname\fR,...]\fR" 4m
.br
Name of input vector map(s)
.IP "\fBoutput\fR=\fIname\fR" 4m
.br
Name for output vector map
.IP "\fBbbox\fR=\fIname\fR" 4m
.br
Name for output vector map where bounding boxes of input vector maps are written to
.PP
.SH DESCRIPTION
\fIv.patch\fR allows the user to combine any number of
vector maps together to create one composite vector
map. If the table structures are identical, attributes are
transferred to the new table.
.SH NOTES
Any vectors that are duplicated among the maps being
patched together (e.g., border lines) will have to be
edited or removed after \fIv.patch\fR is run. Such
editing can be done automatically using
\fIv.clean\fR.
.PP
Lines may need to be
snapped with \fIv.clean
tool=snap,break,rmdupl\fR.
.PP
Boundaries may need to be cleaned with
\fIv.clean tool=break,rmdupl,rmsa\fR
repeatedly until the \fIrmsa\fR tool (Remove small angles at nodes)
no longer modifies any boundaries. If vector topology is still not
clean, boundaries may also need to be snapped with
\fIv.clean tool=snap,break,rmdupl\fR.
.PP
When using the \fI-a\fR flag, the user has to make sure that the
features in the different maps added to the output map do not have
overlapping category numbers, unless identical category numbers
reflect identical attributes, otherwise the attributes of the added
maps are lost. To avoid this, the user can use \fIv.category
option=sum\fR to change category values of some of the maps before
patching.
.SH EXAMPLES
Patch together two maps with mixed feature types:
\fC
.DS
.br
   v.patch input=geology,streams out=geol_streams
.br
.DE
\fR
.br
Append one map to another:
\fC
.DS
.br
   g.copy vect=roads,transport
.br
   v.patch -a input=railroads output=transport --overwrite
.br
.DE
\fR
.SH SEE ALSO
\fIv.clean\fR,
\fIv.build\fR,
\fIv.select\fR,
\fIv.overlay\fR
.SH AUTHORS
Dave Gerdes, U.S.Army Construction Engineering 
Research Laboratory
.br
Radim Blazek, ITC-Irst, Trento, Italy
.PP
\fILast changed: $Date: 2011-11-08 12:29:50 +0100 (Tue, 08 Nov 2011) $\fR
.PP
Full index
.PP
© 2003-2011 GRASS Development Team