r3.univar(1)

📦
version 8.4.2 · 10 versions
, in fedora 44

✨ NAME ✨

hiii bestie 💖 welcome to the GRASS GIS User's Manual page for r3.univar — she's that girl fr fr. She calculates univariate statistics from the non-null cells of a 3D raster map. 🦋

And the stats she's serving? literally the number of cells counted, minimum and maximum cell values, range, arithmetic mean, population variance, standard deviation, coefficient of variation, and sum. no cap. 👑

🏷️ KEYWORDS 🏷️

raster3d, statistics, univariate statistics — iykyk 🌸

🎀 SYNOPSIS 🎀

r3.univar
r3.univar --help
r3.univar [-get] map=name  [zones=name]   [output=name]
[percentile=float[,float,...]]   [separator=character]   [--overwrite]
[--help]  [--verbose]  [--quiet]  [--ui]

🚩 Flags 🚩

  • -g — prints the stats in shell script style 💅
  • -e — calculates extended statistics ✨ (this is the one that eats your RAM, we'll get to that)
  • -t — table output format instead of the standard output format 🎀
  • --overwrite — allow output files to overwrite existing files 🙈 (yes she will simply delete the old one, be warned)
  • --help — print usage summary 🫶
  • --verbose — verbose module output 👀
  • --quiet — quiet module output 🤫
  • --ui — force launching GUI dialog 🖥️

📋 Parameters 📋

  • map=name [required] — name of 3D raster map 🗺️ (this one is not optional bestie, she needs a map)
  • zones=name — 3D Raster map used for zoning, must be of type CELL 🌈
  • output=name — name for output file (if omitted or - output to stdout) 💾
  • percentile=float[,float,...] — percentile to calculate (requires extended statistics flag) 📊
    • Options: 0-100
    • Default: 90
  • separator=character — field separator 🎀
    • Special characters: pipe, comma, space, tab, newline
    • Default: pipe

💖 DESCRIPTION 💖

okay so here's the tea ☕ — r3.univar calculates the univariate statistics for a 3D raster map. That includes the number of cells counted, minimum and maximum cell values, range, arithmetic mean, population variance, standard deviation, coefficient of variation, and sum. the whole lil squad. 💅

And here's the cute part: statistics are calculated separately for every category/zone found in the zones input map, if you gave one. so yes, per-zone glow-ups. ✨

  • if the -e extended statistics flag is given, the 1st quartile, median, 3rd quartile, and the given percentile are calculated 🎀
  • if the -g flag is given, the results are presented in a format suitable for use in a shell script 🐚
  • if the -t flag is given, the results are presented in tabular format with the given field separator 📋

The table can immediately be converted to a vector attribute table which can then be linked to a vector, e.g. the vector that was rasterized to create the zones input raster. it's giving pipeline. 🌈

📝 NOTES 📝

⚠️ As with most GRASS raster3d modules, r3.univar operates on the voxel array defined by the current 3d region settings, not the original extent and resolution of the input map. See g.region. 🫶
⚠️ This module can use large amounts of system memory when the -e extended statistics flag is used with a very large region setting. If the region is too large the module should exit gracefully with a memory allocation error. Basic statistics can be calculated using any size input region. 💀

🌈 EXAMPLE 🌈

Computing univariate statistics of a 3D raster with randomly generated values 🎲:

# define volume
g.region n=10 s=0 w=0 e=10 b=0 t=10 res=1 res3=1 -p3
# generate random map
r3.mapcalc "random_0_1 = rand(0., 1)" -s
# compute univariate statistics, along with extended statistics
r3.univar -e map=random_0_1 percentile=98

and the output she serves ✨:

 100%
total null and non-null cells: 1000
total null cells: 0
Of the non-null cells:
----------------------
n: 1000
minimum: 0.00053905
maximum: 0.998322
range: 0.997783
mean: 0.513676
mean of absolute values: 0.513676
standard deviation: 0.289969
variance: 0.0840821
variation coefficient: 56.4498 %
sum: 513.676463040334
1st quartile: 0.257654
median (even number of cells): 0.524313
3rd quartile: 0.763637
98th percentile: 0.982924

and now the script-style era 💅:

# script style output, along with extended statistics
r3.univar -ge map=random_0_1 percentile=98
n=1000
null_cells=0
cells=1000
min=0.000539049520323687
max=0.998322037540536
range=0.997782988020212
mean=0.513676463040334
mean_of_abs=0.513676463040334
stddev=0.289969154194666
variance=0.0840821103843701
coeff_var=56.4497646005434
sum=513.676463040334
first_quartile=0.257654
median=0.524313
third_quartile=0.763637
percentile_98=0.982924

🚧 TODO 🚧

To be implemented: mode, skewness, kurtosis. 🙈 (not yet bestie, not yet)

👀 SEE ALSO 👀

  • g.region
  • r.univar
  • r.mode
  • r.quantile
  • r.series
  • r3.stats
  • r.statistics
  • v.rast.stats
  • v.univar

👑 AUTHORS 👑

  • Soeren Gebbert
  • Code is based on r.univar from Hamish Bowman, Otago University, New Zealand
  • and Martin Landa
  • Zonal loop by Markus Metz

📦 SOURCE CODE 📦

Available at: r3.univar source code (history) 🌐

Accessed: Saturday Jan 17 05:41:05 2026 ⭐

Main index | 3D raster index | Topics index | Keywords index | Graphical index | Full index 🎀

okay that's the whole page bestie, you ate it, go calculate some stats 💖

signing off from GRASS 8.4.2 — this was r3.univar(1), mwah 💅✨

© 2003-2025 GRASS Development Team, GRASS GIS 8.4.2 Reference Manual 🫶🌸

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