SpeciesDistributionModels.jl aims to provide a flexible and easy-to-use pipeline for fitting, evaluation, and using species distribution models. It is based on the MLJ ecosystem and integrated with Rasters.jl.
This package is still very much work in progress.
The following example models the distribution of Anopheles nili, a malaria vector mosquito distributed in the tropical regions of Africa.
We'll use several other packages in addition to SpeciesDistributionModels
using SpeciesDistributionModels, Rasters, RasterDataSources, GBIF2, LibGEOS, ArchGDAL, StatsBase
import SpeciesDistributionModels as SDMWe start by extracting occurrence records from GBIF using GBIF2.
# extract occurrence records for Anopheles rufipes
nili = species_match("Anopheles nili")
occurrences = occurrence_search(nili, hasCoordinate = true, year = (1990, 2020), limit = 1000)
presence_points = unique(occurrences.geometry)The region of interest will be defined by a convex hull around our presence points, buffered by 5 degrees.
roi = buffer(convexhull(MultiPoint(LibGEOS.to_geos.(presence_points))), 5)Now we'll load bioclimatic variables from WorldClim, using RasterDataSources and Rasters.
# load bioclimatic variables
bio = crop(RasterStack(WorldClim{BioClim}); to = roi)
The extract function from Rasters makes it easy to extract the variables at our presence points.
# get values at presence points
presences = extract(bio, presence_points; skipmissing = true, geometry = false)For background (pseudo-absence) points, we draw 300 points uniformly distributed within the region of interest.
# get a raster with dimensions of bio that is true for all cells within roi and where bio is not missing
roi_raster = rasterize(roi; to = bio, fill = true, missingval = false) .* Rasters.boolmask(bio)
# draw random cells in the region of interest
background_points = sample(DimIndices(roi_raster), weights(roi_raster), 300)
# get bioclimatic variables at the background locations
background = map(p -> bio[p...], background_points)Let's choose some settings for modelling. Here we're using 4 different models, resample using 3-fold stratified cross-validation, and use 3 predictor variables.
# choose models, a resampler, and predictor variables
models = [SDM.linear_model(), SDM.random_forest(), SDM.random_forest(; max_depth = 3), SDM.boosted_regression_tree()]
resampler = StratifiedCV(; nfolds = 3)
predictors = (:bio1, :bio7, :bio12)Now we're ready to run the models. We construct an ensemble using the sdm function.
# run models and construct ensemble
ensemble = sdm(presences, background; models, resampler, predictors)When an ensemble is printed it shows some basic information.
SDMensemble with 12 machines across 4 groups
Occurence data: Presence-Absence with 27 presences and 300 absences
Predictors: bio1 (Continuous), bio7 (Continuous), bio12 (Continuous)
┌────────────────┬──────────────┬──────────┐
│ model │ resampler │ machines │
├────────────────┼──────────────┼──────────┤
│ Linear │ StratifiedCV │ 3 │
│ RandomForest_1 │ StratifiedCV │ 3 │
│ RandomForest_2 │ StratifiedCV │ 3 │
│ EvoTree │ StratifiedCV │ 3 │
└────────────────┴──────────────┴──────────┘
To see how our models performed, use the evaluate function. Here we use it with default settings.
evaluation = SDM.evaluate(ensemble)SDMensembleEvaluation with 4 performance measures
train
┌────────────────┬──────────┬──────────┬───────────┬──────────┐
│ model │ accuracy │ auc │ log_loss │ kappa │
│ Symbol │ Float64 │ Float64 │ Float64 │ Float64 │
├────────────────┼──────────┼──────────┼───────────┼──────────┤
│ Linear │ 0.912844 │ 0.692685 │ 0.265474 │ 0.179984 │
│ RandomForest_1 │ 1.0 │ 1.0 │ 0.0619646 │ 1.0 │
│ RandomForest_2 │ 0.955657 │ 0.936343 │ 0.288469 │ 0.665568 │
│ EvoTree │ 1.0 │ 1.0 │ 0.0115611 │ 1.0 │
└────────────────┴──────────┴──────────┴───────────┴──────────┘
test
┌────────────────┬──────────┬──────────┬──────────┬──────────┐
│ model │ accuracy │ auc │ log_loss │ kappa │
│ Symbol │ Float64 │ Float64 │ Float64 │ Float64 │
├────────────────┼──────────┼──────────┼──────────┼──────────┤
│ Linear │ 0.908257 │ 0.672963 │ 0.273263 │ 0.170727 │
│ RandomForest_1 │ 0.966361 │ 0.876296 │ 0.178809 │ 0.738267 │
│ RandomForest_2 │ 0.938838 │ 0.773333 │ 0.649535 │ 0.404121 │
│ EvoTree │ 0.95107 │ 0.875185 │ 0.25651 │ 0.630953 │
└────────────────┴──────────┴──────────┴──────────┴──────────┘
Finally, we predict back to a raster, taking the simple mean of all models to generate a final prediction.
pr = SDM.predict(ensemble, bio; reducer = mean)252×166 Raster{Union{Missing, Float64},2} with dimensions:
X Projected{Float64} LinRange{Float64}(-17.1667, 24.6667, 252) ForwardOrdered Regular
Intervals{Start} crs: WellKnownText,
Y Projected{Float64} LinRange{Float64}(17.3333, -10.1667, 166) ReverseOrdered Regular
Intervals{Start} crs: WellKnownText
extent: Extent(X = (-17.166666666666686, 24.83333333333334), Y = (-10.166666666666671, 17.500000000000004))
missingval: missing
crs: GEOGCS["WGS 84",DATUM["WGS_1984",SPHEROID["WGS 84",6378137,298.257223563,AUTHORITY["EPSG","7030"]],AUTHORITY["EPSG","6326"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AXIS["Latitude",NORTH],AXIS["Longitude",EAST],AUTHORITY["EPSG","4326"]]
parent:
17.3333 17.1667 … -9.83333 -10.0 -10.1667
-17.1667 missing missing missing missing missing
-17.0 missing missing missing missing missing
-16.8333 missing missing missing missing missing
⋮ ⋱
24.1667 0.00273958 0.00528863 … 0.00558025 0.00578908 0.00613832
24.3333 0.00357797 0.00445221 0.00637058 0.00660174 0.00547219
24.5 0.00610894 0.00443861 0.00616782 0.00583453 0.00602396
24.6667 0.00440761 0.00360355 0.00649026 0.00615647 0.00665752