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r.regression.line.1grass
Langue: en
Version: 330558 (ubuntu - 24/10/10)
Section: 1 (Commandes utilisateur)
NAME
r.regression.line - Calculates linear regression from two raster maps: y = a + b*xKEYWORDS
raster, statisticsSYNOPSIS
r.regression.liner.regression.line help
r.regression.line [-gs] map1=string map2=string [output=string] [--verbose] [--quiet]
Flags:
- -g
Print in shell script style- -s
Slower but accurate (applies to FP maps only)- --verbose
Verbose module output- --quiet
Quiet module output
Parameters:
- map1=string
Map for x coefficient- map2=string
Map for y coefficient- output=string
ASCII file for storing regression coefficients (output to screen if file not specified).
DESCRIPTION
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), residuals (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).NOTES
The flag -s select the slower method (applies to FP maps only) which writes out all pixel values individually to the temporary file. The results for offset/intercept (a) and gain/slope (b) are then identical to that obtained from R-stats's lm() function.EXAMPLE
Comparison of the old and the new DEM in Spearfish:g.region rast=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 rast=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
AUTHOR
Dr. Agustin Lobo - alobo at ija.csic.esUpdated to GRASS 5.7 Michael Barton, Arizona State University
Script style output Markus Neteler
Last changed: $Date: 2008-01-28 09:24:54 +0100 (lun, 28 gen 2008) $
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