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r.stats.zonal(1grass) GRASS GIS User's Manual r.stats.zonal(1grass)

NAME

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

KEYWORDS

raster, statistics, zonal statistics

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:


Cover values extracted from the category labels of the cover map

Create reclass map with statistics as category labels

Allow output files to overwrite existing files

Print usage summary

Verbose module output

Quiet module output

Force launching GUI dialog

Parameters:


Name of base raster map

Name of cover raster map

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

Resultant raster map

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).

SEE ALSO

  • r.stats.quantile for computing quantiles in zones (objects in base raster map),
  • r.quantile for computing quantiles of a whole raster map,
  • r.statistics for categorical (integer) zonal statistics,
  • r.univar for zonal statistics with textual (non-spatial) output,
  • v.vect.stats for statistics of vector points in vector areas.

AUTHOR

Glynn Clements

SOURCE CODE

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

Accessed: Thursday Mar 07 18:15:22 2024

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GRASS 8.3.2