WRAP

The wrap library wraps the GTSAM library into a Python library or MATLAB toolbox. It was designed to be more general than just wrapping GTSAM. For notes on creating a wrap interface, see gtsam.h for what features can be wrapped into a toolbox, as well as the current state of the toolbox for GTSAM.

Prerequisites

Pybind11 and pyparsing

1. This library uses pybind11, which is included as a subdirectory in GTSAM.
2. The interface_parser.py in this library uses pyparsing to parse the interface file gtsam.h. Please install it first in your current Python environment before attempting the build.

python3 -m pip install pyparsing

Getting Started

Clone this repository to your local machine and perform the standard CMake install:

mkdir build && cd build
cmake ..
make install # use sudo if needed

Using wrap in your project is straightforward from here. In your CMakeLists.txt file, you just need to add the following:

find_package(gtwrap)

set(interface_files ${PROJECT_SOURCE_DIR}/cpp/${PROJECT_NAME}.h)

pybind_wrap(${PROJECT_NAME}_py # target
            "${interface_files}" # list of interface header files
            "${PROJECT_NAME}.cpp" # the generated cpp
            "${PROJECT_NAME}" # module_name
            "${PROJECT_MODULE_NAME}" # top namespace in the cpp file e.g. gtsam
            "${ignore}" # ignore classes
            ${PROJECT_BINARY_DIR}/${PROJECT_NAME}.tpl # the wrapping template file
            ${PROJECT_NAME} # libs
            "${PROJECT_NAME}" # dependencies
            ON # use boost serialization
            )

For more information, please follow our tutorial.

Documentation

Documentation for wrapping C++ code can be found here.

Python Wrapper

WARNING: On macOS, you have to statically build GTSAM to use the wrapper.

1. Set GTSAM_BUILD_PYTHON=ON while configuring the build with cmake.

2. What you can do in the build folder:

   1. Just run python then import GTSAM and play around:

      import gtsam
      gtsam.__dir__()

   2. Run the unittests:

      python -m unittest discover

   3. Edit the unittests in python/gtsam/*.py and simply rerun the test. They were symlinked to <build_folder>/gtsam/*.py to facilitate fast development. python -m unittest gtsam/tests/test_Pose3.py - NOTE: You might need to re-run cmake .. if files are deleted or added.

3. Do make install and cd <gtsam_install_folder>/python. Here, you can:

   1. Run the unittests:

      python setup.py test

   2. Install gtsam to your current Python environment.

      python setup.py install

      • NOTE: It's a good idea to create a virtual environment otherwise it will be installed in your system Python's site-packages.

Matlab Wrapper

In the CMake, simply include the MatlabWrap.cmake file.

include(MatlabWrap)

This cmake file defines functions for generating MATLAB wrappers.

• wrap_and_install_library(interfaceHeader linkLibraries extraIncludeDirs extraMexFlags) Generates wrap code and compiles the wrapper.

Usage example:

`wrap_and_install_library("lba.h" "" "" "")`

Arguments:

• interfaceHeader: The relative or absolute path to the wrapper interface definition file.
• linkLibraries: Any additional libraries to link. Your project library (e.g. lba), libraries it depends on, and any necessary MATLAB libraries will be linked automatically. So normally, leave this empty.
• extraIncludeDirs: Any additional include paths required by dependent libraries that have not already been added by include_directories. Again, normally, leave this empty.
• extraMexFlags: Any additional flags to pass to the compiler when building the wrap code. Normally, leave this empty.

Git subtree and Contributing

*WARNING*: Running the ./update_wrap.sh script from the GTSAM repo creates 2 new commits in GTSAM. Be sure to NOT push these directly to master/develop. Preferably, open up a new PR with these updates (see below).

The wrap library is included in GTSAM as a git subtree. This means that sometimes the wrap library can have new features or changes that are not yet reflected in GTSAM. There are two options to get the most up-to-date versions of wrap:

1. Clone and install the wrap repository. For external projects, make sure cmake is using the external wrap rather than the one pre-packaged with GTSAM.
2. Run ./update_wrap.sh from the root of GTSAM's repository to pull in the newest version of wrap to your local GTSAM installation. See the warning above about this script automatically creating commits.

To make a PR on GTSAM with the most recent wrap updates, create a new branch/fork then pull in the most recent wrap changes using ./update_wrap.sh. You should find that two new commits have been made: a squash and a merge from master. You can push these (to the non-develop branch) and open a PR.

For any code contributions to the wrap project, please make them on the wrap repository.