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)

       Accessed: Mon Jun 13 15:09:42 2022

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       © 2003-2022 GRASS Development Team, GRASS GIS 8.2.0 Reference Manual