r.stats.quantile - Compute category quantiles using two passes.

NAME  KEYWORDS  SYNOPSIS  Flags:  Parameters:  DESCRIPTION  NOTES  EXAMPLE  REFERENCES  SEE ALSO  AUTHORS  SOURCE CODE 

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NAME

r.stats.quantile − Compute category quantiles using two passes.

KEYWORDS

raster, statistics, zonal statistics, percentile, quantile

SYNOPSIS

r.stats.quantile
r.stats.quantile −−help
r.stats.quantile [−rpt] base=name cover=name [quantiles=integer] [percentiles=float[,float,...]] [bins=integer] [output=name[,name,...]] [file=name] [separator=character] [−−overwrite] [−−help] [−−verbose] [−−quiet] [−−ui]

Flags:

−r

Create reclass map with statistics as category labels

−p

Do not create output maps; just print statistics

−t

Print statistics in table format

−−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

quantiles=integer

Number of quantiles

percentiles=float[,float,...]

List of percentiles
Default: 50

bins=integer

Number of bins to use
Default: 1000

output=name[,name,...]

Resultant raster map(s)

file=name

Name for output file (if omitted or "−" output to stdout)

separator=character

Field separator
Special characters: pipe, comma, space, tab, newline
Default: :

DESCRIPTION

r.stats.quantile is a tool to analyse exploratory statistics of a floating−point "cover layer" according to how it intersects with objects in a "base layer". It provides quantile calculations as selected "zonal statistics".

NOTES

r.stats.quantile is intended to be a partial replacement for r.statistics, with support for floating−point cover maps. It provides quantile calculations, which are absent from r.stats.zonal.

Quantiles are calculated following algorithm 7 from Hyndman and Fan (1996), which is also the default in R and numpy.

EXAMPLE

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

g.region raster=zipcodes −p
# print quantiles
r.stats.quantile base=zipcodes cover=elevation quantiles=3 −p
27511:0:33.333333:134.717392
27511:1:66.666667:143.985723
27513:0:33.333333:140.669993
27513:1:66.666667:146.279449
27518:0:33.333333:115.140101
27518:1:66.666667:129.893723
[...]
# write out percentile raster maps
r.stats.quantile base=zipcodes cover=elevation percentiles=25,50,75 \
  output=zipcodes_elev_q25,zipcodes_elev_q50,zipcodes_elev_q75

REFERENCES

	•		Hyndman and Fan (1996) Sample Quantiles in Statistical Packages, American Statistician. American Statistical Association. 50 (4): 361−365. DOI: 10.2307/2684934
	•		Engineering Statistics Handbook: Percentile, NIST

SEE ALSO

r.quantile, r.stats.zonal, r.statistics

AUTHORS

Glynn Clements
Markus Metz

SOURCE CODE

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

Latest change: Tuesday Dec 17 20:17:20 2024 in commit: d962e90c026708a4815ea2b9f46c0e84c17de22d

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