NAME
r.regression.line - Calculates linear regression from two raster maps: y = a + b*x.
KEYWORDS
raster,
statistics
SYNOPSIS
r.regression.line
r.regression.line --help
r.regression.line [-g] mapx=name mapy=name [output=name] [--overwrite] [--help] [--verbose] [--quiet] [--ui]
Flags:
- -g
- Print in shell script style
- --overwrite
- Allow output files to overwrite existing files
- --help
- Print usage summary
- --verbose
- Verbose module output
- --quiet
- Quiet module output
- --ui
- Force launching GUI dialog
Parameters:
- mapx=name [required]
- Map for x coefficient
- mapy=name [required]
- Map for y coefficient
- output=name
- ASCII file for storing regression coefficients (output to screen if file not specified).
r.regression.line Calculates linear regression from two raster maps,
according to the formula y = a + b*x, where x and y represent raster maps.
Optionally saves regression coefficients to an ASCII file.
The result includes the following coefficients:
offset/intercept (a) and gain/slope (b), correlation coefficient (R),
number of elements (N), means (medX, medY), standard deviations
(sdX, sdY), and the F test for testing the significance of the
regression model as a whole (F).
The results for offset/intercept (a) and gain/slope (b) are
identical to that obtained from R-stats's lm() function.
Comparison of the old and the new DEM in Spearfish:
g.region raster=elevation.10m -p
r.regression.line map1=elevation.dem map2=elevation.10m
Using the script style flag AND eval to make results
available in the shell:
g.region raster=elevation.10m -p
eval `r.regression.line -g map1=elevation.dem map2=elevation.10m`
echo $a
479.615
echo $b
0.645631
echo $R
0.804441
Dr. Agustin Lobo - alobo at ija.csic.es
Updated to GRASS 5.7 Michael Barton, Arizona State University
Script style output Markus Neteler
Conversion to C module Markus Metz
Last changed: $Date: 2014-12-19 22:55:37 +0100 (Fri, 19 Dec 2014) $
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