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v.kcv - Randomly partition points into test/train sets.
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
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.
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.
v.random and g.region
James Darrell McCauley , when he was at: Agricultural Engineering Purdue University Update to 5.7 Radim Blazek 10 / 2004 Last changed: $Date: 2011-11-08 01:42:51 -0800 (Tue, 08 Nov 2011) $ Full index © 2003-2013 GRASS Development Team