ForTyp

A C++ implementation of the Arner et al. 2001 forest typing algorithm.

This library is largely translated from the FVS codebase (stkval.f and fortyp.f) but also references the Arner documents.

Variable names were kept the same as the FVS FORTRAN code. There are a number of unused variables in the original code that are included but commented out.

Functions

The library provides a function forest_type(treelist, false) which uses DBH, species (using FIA numeric codes), and TPA expansion values and returns the forest type classification. Due to some implementation details, there is a second bool parameter to simulate southern variant specific logic.

There are also convenience lookup tables to convert between forest type, forest type group, and their text names.

fortyp_name() returns the string name of a given forest type code fortypgroup() returns the forest type group int of a given forest type fortypgroup_name() returns the string name of a given forest type group code

If the forest type code is not found, it will just return a null string.

Compilation Instructions

A library libfortyp can be built using CMake and supports out-of-source builds.

git clone

cd fortyp

mkdir build #or whatever you want to call it

cd build

cmake .. #add -DBUILD_SHARED_LIBS=ON for shared library, otherwise will be static

make

Demo

There is a small demo with some example data included in the demo folder. To compile the demo replace the cmake statement above with:

cmake -DBUILD_DEMO=ON ..

which can then be executed by running the ./demo_stocking executable.

Calling from other languages

Python

from ctypes import *
fortyplib = cdll.LoadLibrary("./path/to/libfortyp.so")

#convert a forest type to forest type group
fortyplib.fortypgroup.restype = c_int
fortyplib.fortypgroup.argtypes = [c_int]
fortyplib.fortypgroup(101) #100

#get the name of a forest type group
fortyplib.fortypgroup_name.restype = c_char_p
fortyplib.fortypgroup_name.argtypes = [c_int]
fortyplib.fortypgroup_name(200).decode("utf-8") #"Douglas-fir"

#get the name of a forest type
fortyplib.fortyp_name.restype = c_char_p
fortyplib.fortyp_name.argtypes = [c_int]
fortyplib.fortyp_name(201).decode("utf-8") #"Douglas-fir"

Julia

using Libdl
lib = Libdl.dlopen("./build2/lib/libfortyp.so")

ccall(Libdl.dlsym(lib, :fortypgroup), Int32, (
    Ref{Cint},
), Ptr{Cint}(201))


x1 = ccall(Libdl.dlsym(lib, :fortypgroup_name), Ptr{UInt8}, (
    Ref{Cint},
), Ptr{Cint}(200))

unsafe_string(x1)

x2 = ccall(Libdl.dlsym(lib, :fortyp_name), Ptr{UInt8}, (
    Ref{Cint},
), Ptr{Cint}(201))

unsafe_string(x2)

TO DO?:

1. generalize and clean up input structure
2. add some error handling to map lookups
3. cleaner way to handle variant logic?
4. add python / R interop examples

PRs/issues welcome