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# r.quantile.1grass - Man Page

Compute quantiles using two passes.

## Keywords

raster, algebra, statistics, percentile, quantile

## Synopsis

`r.quantiler.quantile --helpr.quantile [-r] input=name  [quantiles=integer]   [percentiles=float[,float,...]]   [bins=integer]   [file=name]   [--overwrite]  [--help]  [--verbose]  [--quiet]  [--ui]`

### Flags

-r

Generate recode rules based on quantile-defined intervals

--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

input=nameÂ [required]

Name of input raster map

quantiles=integer

Number of quantiles
Default: 4

percentiles=float[,float,...]

List of percentiles

bins=integer

Number of bins to use
Default: 1000000

file=name

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

## Description

r.quantile computes quantiles in a manner suitable for use with large amounts of data. It is using two passes.

## Notes

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

## Example

Calculation of elevation quantiles (printed to standard-out):

```g.region raster=elevation -p
r.quantile input=elevation percentiles=0.1,1,10,25,50,75,90,99,99.9```

The output of r.quantile can be used for quantile classification:

```g.region raster=elevation -p
r.quantile elevation quantiles=5 -r --quiet | r.recode elevation \
out=elev_quant5 rules=-```

## 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

r.mode, r.quant, r.recode, r.series, r.stats, r.stats.quantile, r.stats.zonal, r.statistics, r.univar, v.rast.stats

Glynn Clements
Markus Metz

## Source Code

Available at: r.quantile source code (history)

Accessed: Tuesday May 14 13:40:30 2024

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Â© 2003-2024 GRASS Development Team, GRASS GIS 8.3.2 Reference Manual

## Info

GRASS 8.3.2 GRASS GIS User's Manual