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spatial-casadi

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This package implements various data structures and helper methods for manipulating spatial transformations using CasADi variables in Python. The library interface is partially based on the Scipy spatial module.

Examples

There are three main data structures: Rotation, Translation, and Transformation. The following showcases some of the main functionality of the library.

>>> import spatial_casadi as sc
>>> import casadi as cs
>>> cs.np.random.seed(10)
>>> euler = cs.SX.sym("euler", 3)
>>> sc.Rotation.from_euler('xyz', euler).as_quat()
SX(@1=2, @2=cos((x_2/@1)), @3=cos((x_1/@1)), @4=sin((x_0/@1)), @5=(@3*@4), @6=sin((x_2/@1)), @7=cos((x_0/@1)), @8=sin((x_1/@1)), @9=(@7*@8), @10=(@3*@7), @11=(@8*@4), [((@2*@5)-(@6*@9)), ((@2*@9)+(@6*@5)), ((@10*@6)-(@2*@11)), ((@2*@10)+(@6*@11))])
>>> r = sc.Rotation.random()
>>> r.as_quat()
DM([0.615982, 0.330883, -0.71489, -0.0038783])
>>> r.as_rotvec()
DM([-1.9304, -1.03694, 2.24037])
>>> r.as_matrix()
DM(
[[-0.241103, 0.40209, -0.883285],
 [0.41318, -0.781003, -0.468312],
 [-0.878152, -0.477867, 0.0221665]])
>>> r.as_euler('xyz')
DM([-1.52444, 1.07199, 2.09902])
>>> r.as_mrp()
DM([-0.613602, -0.329604, 0.712128])
>>> sc.Rotation.from_euler('x', 90, degrees=True).as_matrix()
DM(
[[1, 0, 0],
 [0, 2.22045e-16, -1],
 [0, 1, 2.22045e-16]])
>> r1 = sc.Rotation.random()
>>> r1.as_quat()
DM([0.625459, -0.724863, 0.267273, 0.109269])
>> r2 = sc.Rotation.random()
>>> r2.as_quat()
DM([0.00332548, -0.1353, 0.335557, 0.932247])
>>> (r1 * r2).as_quat()
DM([0.376374, -0.899524, 0.203617, -0.0879736])

Install

From PyPI

$ pip install spatial-casadi
$ pip install spatial-casadi[test] # if you want to run the test scripts

From source

In a new terminal:

  1. Clone repository:
    • (ssh) $ git clone git@github.com:cmower/spatial-casadi.git, or
    • (https) $ git clone https://github.com/cmower/spatial-casadi.git
  2. Change directory: $ cd spatial-casadi
  3. Ensure pip is up-to-date: $ python -m pip install --upgrade pip
  4. Install from source:
    • (main library) $ pip install .
    • (when you want to also run the test scripts) $ pip install .[test]

Running the test scripts

  1. Install spatial-casadi from source and ensure you install the test packages (see previous section).
  2. Change directory: $ cd /path/to/spatial-casadi
  3. Run tests: pytest

Build documentation

The documentation is hosted here. However, if you want to build it yourself, then follow these steps.

In a new terminal:

  1. Clone repository:
    • (ssh) $ git clone git@github.com:cmower/spatial-casadi.git, or
    • (https) $ git clone https://github.com/cmower/spatial-casadi.git
  2. Change directory: $ cd spatial-casadi/doc
  3. Install doxygen: $ sudo apt install doxygen
  4. Build documentation: $ doxygen
  5. View documentation:
    • In a browser, open html/index.html
    • Build pdf (requires LaTeX)
      • $ cd latex
      • $ make
      • Open the file called refman.pdf

Citing

If you use spatial-casadi in your work, please consider citing the following.

@software{Mower2023
  title = "Spatial CasADi: A Compact Library for Manipulating Spatial Transformations",
  author = "Christopher E. Mower",
  year = "2023",
  url = {https://github.com/cmower/spatial-casadi},
}

Contributing

If you have any issues with the library, or find inaccuracies in the documentation please raise an issue. I am happy to consider new features if you fork the library and submit a pull request.