r.stats.quantile.1grass - Man Page
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)
Accessed: Tuesday Mar 19 11:02:02 2024
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