.TH r.resamp.stats 1grass "" "GRASS 6.4.2" "Grass User's Manual"
.SH NAME
\fI\fBr.resamp.stats\fR\fR  - Resamples raster map layers to a coarser grid using aggregation.
.SH KEYWORDS
raster, resample
.SH SYNOPSIS
\fBr.resamp.stats\fR
.br
\fBr.resamp.stats help\fR
.br
\fBr.resamp.stats\fR [-\fBnw\fR] \fBinput\fR=\fIname\fR \fBoutput\fR=\fIname\fR  [\fBmethod\fR=\fIstring\fR]   [--\fBoverwrite\fR]  [--\fBverbose\fR]  [--\fBquiet\fR] 
.SS Flags:
.IP "\fB-n\fR" 4m
.br
Propagate NULLs
.IP "\fB-w\fR" 4m
.br
Weight according to area (slower)
.IP "\fB--overwrite\fR" 4m
.br
Allow output files to overwrite existing files
.IP "\fB--verbose\fR" 4m
.br
Verbose module output
.IP "\fB--quiet\fR" 4m
.br
Quiet module output
.PP
.SS Parameters:
.IP "\fBinput\fR=\fIname\fR" 4m
.br
Name of input raster map
.IP "\fBoutput\fR=\fIname\fR" 4m
.br
Name for output raster map
.IP "\fBmethod\fR=\fIstring\fR" 4m
.br
Aggregation method
.br
Options: \fIaverage,median,mode,minimum,maximum,quart1,quart3,perc90,sum,variance,stddev\fR
.br
Default: \fIaverage\fR
.PP
.SH DESCRIPTION
.PP
\fIr.resamp.stats\fR fills a grid cell (raster) matrix with
aggregated values generated from a set of input layer data points.
.PP
Without the \fI-w\fR switch, the aggregate is computed over all of
the input cells whose centers lie within the output cell.
.PP
With the \fI-w\fR switch, the aggregate uses the values from all
input cells which intersect the output cell, weighted according to the
proportion of the source cell which lies inside the output cell. This
is slower, but produces a more accurate result.
.SH NOTES
.PP
Resampling modules (\fIr.resample, r.resamp.stats, r.resamp.interp,
r.resamp.rst\fR) resample the map to match the current region settings.
.PP
The notion of weighting doesn't make any sense for the min and max
aggregates. However, the \fI-w\fR flag still has significance in
that, when multiple destination cells overlap a source cell, the
source cell is included in the calculation of all of the destination
cells.
.SH EXAMPLE
.PP
Resample elevation raster map to a lower resolution (from 6m to 20m;
North Carolina sample dataset):
\fC
.DS
.br
g.region rast=el_D782_6m -p
.br
g.region res=20 -ap
.br
r.resamp.stats input=el_D782_6m output=el_D782_20m
.br
.DE
\fR
.SH SEE ALSO
\fIg.region\fR,
\fIr.resample\fR,
\fIr.resamp.rst\fR
\fIr.resamp.interp\fR
.SH AUTHOR
Glynn Clements
.PP
\fILast changed: $Date: 2011-11-08 12:29:50 +0100 (Tue, 08 Nov 2011) $\fR
.PP
Full index
.PP
© 2003-2011 GRASS Development Team