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Note: This addon document is for an older version of GRASS GIS that will be discontinued soon. You should upgrade your GRASS GIS installation, and read the current addon manual page.


r.maxent.lambdas - Computes raw or logistic prediction maps from MaxEnt lambdas files


raster, maxent, ecology, niche


r.maxent.lambdas --help
r.maxent.lambdas [-pnNc] lambdas_file=name [alias_file=name] [logistic=name] [raw=name] [ndigits=integer] [nprocs=integer] width=integer height=integer [--overwrite] [--help] [--verbose] [--quiet] [--ui]


Print only
Print mapcalculator expressions and exit
Do not include cells where any variabel contains no data
Do not include cells where all variabels contain no data
Clamp values in raster maps to value range seen by the MaxEnt model
Allow output files to overwrite existing files
Print usage summary
Verbose module output
Quiet module output
Force launching GUI dialog


lambdas_file=name [required]
MaxEnt lambdas-file to compute distribution-model from
CSV-file to replace alias names from MaxEnt by GRASS map names
Raster map with logistic output
Raster map with raw output
Produce logistic output as integer map with this number of digits preserved
Default: 0
Number of r.mapcalc processes to run in parallel (requires r.mapcalc.tiled addon)
Options: 1-
Default: 1
width=integer [required]
Width of tiles (columns) (requires r.mapcalc.tiled addon and nprocs > 1)
Default: 1000
height=integer [required]
Height of tiles (requires r.mapcalc.tiled addon and nprocs > 1)
Default: 1000

Table of contents


The script is intended to compute (raw) or (logistic) prediction maps from a lambdas file produced with MaxEnt >= 3.3.3e.

It will parse the specified lambdas_file from MaxEnt >= 3.3.3e and translate it into an r.mapcalc-expression. If alias names had been used in MaxEnt, these alias names can automatically be replaced according to a CSV-like file (alias_file) provided by the user, as it can be produced with r.out.maxent_swd. This file should contain alias names in the first column and map names in the second column, separated by comma, without header. It should look e.g. like this:


If such a CSV-file with alias names used in MaxEnt is provided, the alias names from MaxEnt are replaced by raster map names.

The logistic map can be produced as an integer map. To do so the user has to specify the number of decimal places, that should be preserved in integer output in the ndigits option.

Optionally the map calculator expressions can be printed to stdout with the p-flag for inspection or documentation as they likely exceed the space in the map history.

By default, NoData for each function in the lambdas file is set to zero. The user can however choose to set pixels to null where a single variable contains NoData (n-flag) or where all variables produce NoData (N-flag).

Extraction of random points in MaxEnt can be a reason why values in raster maps exceed values seen by the MaxEnt model. To limit raster map values to the valid range for the model, raster map values can be clamped to the value range in the model with the c-flag.

Complex models (and thus mapcalculator expressions) can become CPU intensive to process. On multicore computers, processing such large models can benefit from tiled, parallel processing (nprocs larger than 1). This requires that the r.mapcalc.tiled addon is installed. The size of tiles can be controlled by the height and width options.


This script works only if the maps containing the input data to MaxEnt are accessible from the current region.

Due to conversion from double to floating-point in exp()-function, a loss of precision from the 7th decimal place onwards may occur in the logistic output. Differences to logistic predictions from MaxEnt are supposed to be below 0.0001. This can be checked by importing sample or background predictions from the MaxEnt output (e.g. with


SEE ALSO, r.mapcalc, r.mapcalc.tiled (Addon) r.out.maxent_swd (Addon)


Stefan Blumentrath, Norwegian Institute for Nature Research (NINA),


Available at: r.maxent.lambdas source code (history)

Latest change: Thu Jan 20 09:33:13 2022 in commit: 7b6b663aa15fbce651ea6aa364676676e25c81ac

Note: This addon document is for an older version of GRASS GIS that will be discontinued soon. You should upgrade your GRASS GIS installation, and read the current addon manual page.

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