.TH v.patch 1grass "" "GRASS 7.8.5" "GRASS GIS User's Manual"
.SH NAME
\fI\fBv.patch\fR\fR  \- Creates a new vector map by combining other vector maps.
.SH KEYWORDS
vector, geometry, level1
.SH SYNOPSIS
\fBv.patch\fR
.br
\fBv.patch \-\-help\fR
.br
\fBv.patch\fR [\-\fBnzeab\fR] \fBinput\fR=\fIname\fR[,\fIname\fR,...] \fBoutput\fR=\fIname\fR  [\fBbbox\fR=\fIname\fR]   [\-\-\fBoverwrite\fR]  [\-\-\fBhelp\fR]  [\-\-\fBverbose\fR]  [\-\-\fBquiet\fR]  [\-\-\fBui\fR]
.SS Flags:
.IP "\fB\-n\fR" 4m
.br
Do not expect input with topology
.br
Applicable when input is points without topology
.IP "\fB\-z\fR" 4m
.br
Expect z coordinate even when not using topology
.br
Applicable when input is points with z coordinate but without topology
.IP "\fB\-e\fR" 4m
.br
Copy also attribute table
.br
Only the table of layer 1 is currently supported
.IP "\fB\-a\fR" 4m
.br
Append files to existing file (overwriting existing files must be activated)
.IP "\fB\-b\fR" 4m
.br
Do not build topology
.br
Advantageous when handling a large number of points
.IP "\fB\-\-overwrite\fR" 4m
.br
Allow output files to overwrite existing files
.IP "\fB\-\-help\fR" 4m
.br
Print usage summary
.IP "\fB\-\-verbose\fR" 4m
.br
Verbose module output
.IP "\fB\-\-quiet\fR" 4m
.br
Quiet module output
.IP "\fB\-\-ui\fR" 4m
.br
Force launching GUI dialog
.SS Parameters:
.IP "\fBinput\fR=\fIname[,\fIname\fR,...]\fR \fB[required]\fR" 4m
.br
Name of input vector map(s)
.br
Or data source(s) for direct OGR access
.IP "\fBoutput\fR=\fIname\fR \fB[required]\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
.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\-e\fR flag, \fIv.patch\fR shifts category (cat)
values in the output so that category numbers from the different input
maps do not overlap. This shift is applied to both the category values
of the features and the category values in the attribute tables. Hence,
there is no need to run \fIv.category\fR
and \fIv.db.update\fR beforehand.
.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:
.br
.nf
\fC
   v.patch input=geology,streams out=geol_streams
\fR
.fi
.br
Append one map to another:
.br
.nf
\fC
   g.copy vect=roads,transport
   v.patch \-a input=railroads output=transport \-\-overwrite
\fR
.fi
.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
.SH SOURCE CODE
.PP
Available at: v.patch source code (history)
.PP
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.PP
© 2003\-2020
GRASS Development Team,
GRASS GIS 7.8.5 Reference Manual