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153 lines
6.2 KiB
153 lines
6.2 KiB
4 years ago
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Metadata-Version: 2.1
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Name: squaternion
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Version: 0.3.2
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Summary: Some simple functions for quaternion math
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Home-page: https://pypi.org/project/squaternion/
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License: MIT
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Keywords: rotations,quaternion,euler
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Author: walchko
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Author-email: walchko@users.noreply.github.com
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Requires-Python: >=3.6
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Classifier: Development Status :: 4 - Beta
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Classifier: Intended Audience :: Developers
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Classifier: License :: OSI Approved :: MIT License
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Classifier: Operating System :: OS Independent
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Classifier: Programming Language :: Python :: 3
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Classifier: Programming Language :: Python :: 3.6
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Classifier: Programming Language :: Python :: 3.7
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Classifier: Programming Language :: Python :: 3.8
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Classifier: Topic :: Software Development :: Libraries
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Classifier: Topic :: Software Development :: Libraries :: Application Frameworks
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Classifier: Topic :: Software Development :: Libraries :: Python Modules
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Requires-Dist: importlib-metadata; python_version < "3.8"
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Project-URL: Repository, http://github.com/MomsFriendlyRobotCompany/squaternion
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Description-Content-Type: text/markdown
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# Simple Quaternions (`squaternion`)
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[](https://github.com/MomsFriendlyRobotCompany/squaternion/actions)
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Generally I don't need all of the capabilities (or complexity) of `quaternion`
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math libraries. Basically I just need a way to convert between Euler and
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Quaternion representations and have a nice way to print them out.
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This has basically no imports outside of standard python 3.x libraries.
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It should be easier to get on embedded python systems without having to build
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`numpy`. Also, this tries to be *fast* by using a frozen class with slots and
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where it makes sense, returns `tuples` instead of `list`s.
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### Alternatives
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This is a basic library that converts between Euler angles and Quaternions.
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There are other libraries that do so much more listed below ... but I don't
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need all of that.
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- [scipy.spatial.transform.Rotation](https://docs.scipy.org/doc/scipy/reference/generated/scipy.spatial.transform.Rotation.html#scipy.spatial.transform.Rotation): has everything you could want, with lots of imports
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- [tinyquaternion](https://github.com/rezaahmadzadeh/tinyquaternion): appears to be more functional but needs `numpy`
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- [quaternions](https://github.com/mjsobrep/quaternions): another good lightweight quaternion package
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- [pyrr](https://github.com/adamlwgriffiths/Pyrr): seems good, integrated with `numpy`
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## Install
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```
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pip install squaternion
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```
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## Usage
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```python
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from squaternion import Quaternion
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# if you know the values you want Quaternion(w, x, y, z), note this is a
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# attr frozen class so it is immutable once created
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q = Quaternion(1,0,0,0)
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# multiplication for scalar (int, double) and with another quaternion
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q = Quaternion(1,2,3,4)
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q*q => Quaternion(w=-28, x=4, y=6, z=8)
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3*q => Quaternion(w=3, x=6, y=9, z=12)
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q*3.0 => Quaternion(w=3.0, x=6.0, y=9.0, z=12.0)
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# Addition and subtraction
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q = Quaternion(1,2,3,4)
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q+q => Quaternion(w=2, x=4, y=6, z=8)
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# numpy can do some things, but it will change the tuple to an array, so you might
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# need to transform it back to a quaternion
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q = Quaternion(1,2,3,4)
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np.dot(q,q) => 30
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np.sqrt(np.dot(q,q)) => 5.477225575051661
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q/np.sqrt(np.dot(q,q)) => array([0.18257419, 0.36514837, 0.54772256, 0.73029674])
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Quaternion(*(q/np.sqrt(np.dot(q,q)))) => Quaternion(w=0.18257418583505536, x=0.3651483716701107, y=0.5477225575051661, z=0.7302967433402214)
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# however you typically don't think in 4 dimensions, so create from
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# euler angles from_eluer(roll, pitch, yaw), default is radians, but set
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# degrees true if giving degrees
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q = Quaternion.from_euler(0, -90, 100, degrees=True)
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# can get the euler angles back out in degrees (set to True)
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e = q.to_euler(degrees=True)
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d = q.to_dict()
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# iterate through values
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for i in q:
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print(f"{i}")
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# indexing like a namedtuple
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z = q[3]
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z = q[-1]
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v = q[-3:]
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w = q[0]
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# class properties
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v = q.vector # returns a tuple (x,y,z)
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s = q.scalar # returns a double (w)
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n = q.normalize # returns unit quaternion
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m = q.magnitude # returns the magnitude of the quaternion
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a = q.angle # returns angle of rotation in radians
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a = q.axis # returns axis of rotation
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# useful attr functions
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q == q # compare will return True
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q != q # will return False
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print(q) # pretty print
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w = q.w
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x = q.x
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y = q.y
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z = q.z
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```
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## References
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- [Wikipedia Convert Between Quaternions and Euler Angles](https://en.wikipedia.org/wiki/Conversion_between_quaternions_and_Euler_angles)
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- [Wikipedia Euler Angle Definitions](https://en.wikipedia.org/wiki/Euler_angles#Conventions_2)
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- [Wikipedia Gimbal Lock](https://en.wikipedia.org/wiki/Gimbal_lock)
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# MIT License
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Copyright (c) 2018 Kevin Walchko
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in all
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copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE.
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