r.stats.zonal - GRASS GIS manual

NAME

r.stats.zonal - Calculates category or object oriented statistics (accumulator-based statistics).

KEYWORDS

SYNOPSIS

r.stats.zonal

r.stats.zonal --help

r.stats.zonal [-cr] base=name cover=name method=string output=name [--overwrite] [--help] [--verbose] [--quiet] [--ui]

Flags:

-c: Cover values extracted from the category labels of the cover map
-r: Create reclass map with statistics as category labels
--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:

base=name [required]: Name of base raster map
cover=name [required]: Name of cover raster map
method=string [required]: Method of object-based statistic; Options: count, sum, min, max, range, average, avedev, variance, stddev, skewness, kurtosis, variance2, stddev2, skewness2, kurtosis2; count: Count of values in specified objects; sum: Sum of values in specified objects; min: Minimum of values in specified objects; max: Maximum of values in specified objects; range: Range of values (max - min) in specified objects; average: Average of values in specified objects; avedev: Average deviation of values in specified objects; variance: Variance of values in specified objects; stddev: Standard deviation of values in specified objects; skewness: Skewness of values in specified objects; kurtosis: Kurtosis of values in specified objects; variance2: (2-pass) Variance of values in specified objects; stddev2: (2-pass) Standard deviation of values in specified objects; skewness2: (2-pass) Skewness of values in specified objects; kurtosis2: (2-pass) Kurtosis of values in specified objects
output=name [required]: Resultant raster map

DESCRIPTION
NOTES
EXAMPLE
SEE ALSO
AUTHOR

DESCRIPTION

r.stats.zonal is a tool to analyse exploratory statistics of a floating-point "cover layer" according to how it intersects with objects in a "base layer". A variety of standard statistical measures are possible. This type of analysis is often called zonal statistics. The zones are specified as the base raster map and the statistics are computed from cells in the cover raster map. Notably, the output of this module is spatial: The resulting values are recorded as cell values in the output raster map.

NOTES

r.stats.zonal is intended to be a partial replacement for r.statistics, with support for floating-point cover maps at the expense of not supporting quantiles. For this, see r.stats.quantile.

EXAMPLE

In this example, the raster polygon map zipcodes in the North Carolina sample dataset is used to calculate zonal raster statistics using the elevation raster map:

g.region raster=zipcodes -p

# pixel count in zipcode areas
r.stats.zonal base=zipcodes cover=elevation method=count output=zipcodes_elev_count
r.colors zipcodes_elev_count color=gyr -g

# average elevation in zipcode areas
r.stats.zonal base=zipcodes cover=elevation method=average output=zipcodes_elev_avg
r.colors zipcodes_elev_avg color=elevation -g

Figure: ZIP code map on the left shows ZIP code areas, elevation map the respective values per pixel, zonal statistics map on the right shows the average elevation per zone (all maps: spatial subset).

AUTHOR

Glynn Clements

SOURCE CODE

Available at: r.stats.zonal source code (history)

Latest change: Wednesday Nov 27 22:53:26 2024 in commit: b90ce69e88409469369ec1edb86fde8ec822af8b