GRASS GIS manual: v.kcv

Note: This document is for an older version of GRASS GIS that is outdated. You should upgrade, and read the current manual page.

NAME

v.kcv - Randomly partition points into test/train sets.

KEYWORDS

vector, statistics, points

SYNOPSIS

v.kcv
v.kcv help
v.kcv [-d] map=name [layer=integer] k=integer [column=name] [--verbose] [--quiet]

Flags:

-d: Use drand48()
--verbose: Verbose module output
--quiet: Quiet module output

Parameters:

map=name: Name of input vector map
layer=integer: Layer number; A single vector map can be connected to multiple database tables. This number determines which table to use.; Default: 1
k=integer: Number of partitions; Must be > 1
column=name: 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 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 k times.

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.

Be warned that random number generation occurs over the intervals defined by the region of the map.

This program may not work properly with Lat-long data.

AUTHOR

James Darrell McCauley <darrell@mccauley-usa.com>,
when he was at: Agricultural Engineering Purdue University

Update to 5.7 Radim Blazek 10 / 2004

Last changed: $Date: 2011-11-08 02:23:26 -0800 (Tue, 08 Nov 2011) $

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