NAME¶
v.kcv - Randomly partition points into test/train sets.
KEYWORDS¶
vector, statistics
SYNOPSIS¶
v.kcv
v.kcv help
v.kcv [-
dq]
input=
name output=
name
k=
integer column=
string [--
overwrite]
[--
verbose] [--
quiet]
Flags:¶
- -d
-
Use drand48()
- -q
-
Quiet
- --overwrite
-
Allow output files to overwrite existing files
- --verbose
-
Verbose module output
- --quiet
-
Quiet module output
Parameters:¶
- input=name
-
Name of input vector map
- output=name
-
Name for output vector map
- k=integer
-
Number of partitions
Options: 1-32767
- column=string
-
Name for new column to which partition number is written
Default: part
DESCRIPTION¶
v.kcv randomly divides a points lists into
k sets of test/train
data (for
k-fold
cross
validation). Test partitions are
mutually exclusive. That is, a point will appear in only one test partition
and
k-1 training partitions. The module 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
k
times.
NOTES¶
An ideal random sites generator will follow a Poisson distribution and will only
be as random as the original sites. This module simply divides vector points
up in a random manner.
Be warned that random number generation occurs over the intervals defined by the
current region of the map.
This program may not work properly with Lat-long data.
EXAMPLES¶
All examples are based on the North Carolina sample dataset.
g.copy vect=geonames_wake,my_geonames_wake
v.kcv input=my_geonames_wake output=my_geonames_wake_kvc column=part k=10
g.copy vect=geodetic_pts,my_geodetic_pts
v.kcv input=my_geodetic_pts output=my_geodetic_pts_kvc column=part k=10
SEE ALSO¶
v.random, g.region
AUTHOR¶
James Darrell McCauley,
when he was at: Agricultural Engineering Purdue University
27 Jan 1994: fixed RAND_MAX for Solaris 2.3
13 Sep 2000: released under GPL
Updated to 5.7 Radim Blazek 10 / 2004
OGR support by Martin Landa (2009)
Speed-up by Jan Vandrol and Jan Ruzicka (2013)
Last changed: $Date: 2014-05-01 22:00:52 +0200 (Thu, 01 May 2014) $
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