r.li.simpson(1grass)

💖 r.li.simpson(1grass) — the whole vibe 💖

okay bestie, so this is r.li.simpson, a GRASS manual page, and it is literally about calculating Simpson's diversity index on a raster map. yes. that Simpson. the diversity one. 🦋

KEYWORDS: raster, landscape structure analysis, diversity index ✨

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🌸 SYNOPSIS 🌸

r.li.simpson
r.li.simpson --help
r.li.simpson input=name config=name output=name  [--overwrite]  [--help]
[--verbose]  [--quiet]  [--ui]

🎀 Flags: 🎀

• --overwrite — lets output files just. overwrite existing files. no respect for the old ones, periodt 💅
• --help — prints the usage summary, aka the "what do I even type" moment
• --verbose — verbose module output, so it tells you everything it's doing, main character energy
• --quiet — quiet module output, the "don't talk to me rn" setting 🤫
• --ui — force launches the GUI dialog, for when clicking > typing

🫶 Parameters: 🫶

• input=name — required. name of input raster map. the map you're vibing with 🗺️
• config=name — required. configuration file. yes you need one.
• output=name — required. name for output raster map.

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✨ DESCRIPTION ✨

r.li.simpson calculates the "Simpson's diversity index" — that's the phrase, quoted like that, in the original — as:

with:

• i: patch type 🍓
• m: number of different patch types
• pi: proportional abundance of patch type i

(yes, the page really does hand you an "as:" and then a "with:" and then just the variable list. that's the whole setup. it's giving mysterious. iykyk 🔥)

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🌈 NOTES 🌈

💀 Do NOT use absolute path names for the config and output file/map parameters. fr fr. just don't.

If the "moving window" method was selected in g.gui.rlisetup, then the output will be a raster map. otherwise?? an ASCII file gets generated in the folder

• C:\Users\userxy\AppData\Roaming\GRASS8\r.li\output\ on MS-Windows 🪟
• $HOME/.grass8/r.li/output/ on GNU/Linux 🐧

Also! If the input raster map contains only NULL values, then r.li.simpson returns NULL. that's it. that's the answer. nothing. NULL. 😭

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💜 EXAMPLES 💜

the basic one 🧚

want Simpson's diversity index on map my_map, using my_conf config file (which you previously defined with g.gui.rlisetup), and saving results in my_out? run:

r.li.simpson input=my_map conf=my_conf output=my_out

Forest map, Spearfish sample dataset 🌲

g.region raster=landcover.30m -p
r.mapcalc "forests = if(landcover.30m >= 41 && landcover.30m <= 43,1,null())"
r.li.simpson input=forests conf=movwindow7 out=forests_simpson_mov7
r.univar forests_simpson_mov7

Forest map, North Carolina sample dataset 🌳

g.region raster=landclass96 -p
r.mapcalc "forests = if(landclass96 == 5, 1, null() )"
r.li.simpson input=forests conf=movwindow7 out=forests_simpson_mov7
# verify
r.univar forests_simpson_mov7
r.to.vect input=forests output=forests type=area
d.mon wx0
d.rast forests_simpson_mov7
d.vect forests type=boundary

not me noticing the examples use conf= and out= while the synopsis says config= and output= — both spellings show up in the original and i am simply reporting the receipts 👑💅

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🌟 SEE ALSO 🌟

• r.li (package overview) — the whole family, go meet them
• g.gui.rlisetup

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📚 REFERENCES 📚

McGarigal, K., and B. J. Marks. 1995. FRAGSTATS: spatial pattern analysis program for quantifying landscape structure. USDA For. Serv. Gen. Tech. Rep. PNW-351. (PDF)

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👑 AUTHORS 👑

• Serena Pallecchi, student of Computer Science University of Pisa (Italy).
• Commission from Faunalia Pontedera (PI), Italy (www.faunalia.it)

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🔥 SOURCE CODE 🔥

Available at: r.li.simpson source code (history)

Latest change: Friday Apr 17 01:04:26 2026 in commit: 32a143358df26b2e518b03c7e0d79541e8d1e5b1

Main index | Raster index | Topics index | Keywords index | Graphical index | Full index

© 2003-2026 GRASS Development Team, GRASS 8.5.0 Reference Manual

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and that's the page, bestie — this was GRASS 8.5.0, r.li.simpson(1grass), go forth and index some diversity 🌸🦋✨🫶