.TH v.kcv 1grass "" "GRASS 6.4.2" "Grass User's Manual"
.SH NAME
\fI\fBv.kcv\fR\fR  - Randomly partition points into test/train sets.
.SH KEYWORDS
vector, statistics
.SH SYNOPSIS
\fBv.kcv\fR
.br
\fBv.kcv help\fR
.br
\fBv.kcv\fR [-\fBdq\fR] \fBinput\fR=\fIname\fR \fBoutput\fR=\fIname\fR \fBk\fR=\fIinteger\fR \fBcolumn\fR=\fIstring\fR  [--\fBoverwrite\fR]  [--\fBverbose\fR]  [--\fBquiet\fR] 
.SS Flags:
.IP "\fB-d\fR" 4m
.br
Use drand48()
.IP "\fB-q\fR" 4m
.br
Quiet
.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\fR" 4m
.br
Name of input vector map
.IP "\fBoutput\fR=\fIname\fR" 4m
.br
Name for output vector map
.IP "\fBk\fR=\fIinteger\fR" 4m
.br
Number of partitions
.br
Options: \fI1-32767\fR
.IP "\fBcolumn\fR=\fIstring\fR" 4m
.br
Name for new column to which partition number is written
.br
Default: \fIpart\fR
.PP
.SH DESCRIPTION
\fIv.kcv\fR  randomly  divides  a  points  lists  into  \fIk\fR sets of
test/train data (for \fBk\fR-fold \fBc\fRross \fBv\fRalidation).
Test  partitions  are  mutually  exclusive.  That  is,  a point will
appear in only one test partition and \fIk-1\fR training  partitions.
The  program  generates  a random point using the selected
random number generator and then finds the closest point to
it.  This site is removed from the candidate list (meaning
that it will not be selected for any other test  set)  and
saved  in the first test partition file.  This is repeated
until enough points have been selected for the test partition.
The  number  of  points  chosen for test partitions
depends upon the number of sites available and the  number
of partitions chosen (this number is made as consistent as
possible while ensuring that all sites will be chosen  for
testing).  This  process of filling up a test partition is
done \fIk\fR times.
.SH NOTES
An ideal random sites generator will follow a Poisson dis
only be as random as the  original  points.   This  program
simply divides points up in a random manner.
.PP
Be  warned  that  random number generation occurs over the
intervals defined by the region of the map.
.PP
This program may not work properly with Lat-long data.
.SH SEE ALSO
\fIv.random\fR and 
\fIg.region\fR
.SH AUTHOR
James Darrell McCauley
,
.br
when he was at: 
Agricultural
Engineering
Purdue University
.PP
Update to 5.7 Radim Blazek 10 / 2004
.PP
\fILast changed: $Date: 2011-11-08 10:42:51 +0100 (Tue, 08 Nov 2011) $\fR
.PP
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.PP
© 2003-2011 GRASS Development Team