# squaternion Release 0.3.2

Some simple functions for quaternion math

Keywords
rotations, quaternion, euler, python
MIT
Install
``` pip install squaternion==0.3.2 ```

# Simple Quaternions (`squaternion`)

Generally I don't need all of the capabilities (or complexity) of `quaternion` math libraries. Basically I just need a way to convert between Euler and Quaternion representations and have a nice way to print them out.

This has basically no imports outside of standard python 3.x libraries. It should be easier to get on embedded python systems without having to build `numpy`. Also, this tries to be fast by using a frozen class with slots and where it makes sense, returns `tuples` instead of `list`s.

### Alternatives

This is a basic library that converts between Euler angles and Quaternions. There are other libraries that do so much more listed below ... but I don't need all of that.

## Install

``````pip install squaternion
``````

## Usage

```from squaternion import Quaternion

# if you know the values you want Quaternion(w, x, y, z), note this is a
# attr frozen class so it is immutable once created
q = Quaternion(1,0,0,0)

# multiplication for scalar (int, double) and with another quaternion
q = Quaternion(1,2,3,4)
q*q => Quaternion(w=-28, x=4, y=6, z=8)
3*q => Quaternion(w=3, x=6, y=9, z=12)
q*3.0 => Quaternion(w=3.0, x=6.0, y=9.0, z=12.0)

# Addition and subtraction
q = Quaternion(1,2,3,4)
q+q => Quaternion(w=2, x=4, y=6, z=8)

# numpy can do some things, but it will change the tuple to an array, so you might
# need to transform it back to a quaternion
q = Quaternion(1,2,3,4)
np.dot(q,q) => 30
np.sqrt(np.dot(q,q)) => 5.477225575051661
q/np.sqrt(np.dot(q,q)) => array([0.18257419, 0.36514837, 0.54772256, 0.73029674])
Quaternion(*(q/np.sqrt(np.dot(q,q)))) => Quaternion(w=0.18257418583505536, x=0.3651483716701107, y=0.5477225575051661, z=0.7302967433402214)

# however you typically don't think in 4 dimensions, so create from
# euler angles from_eluer(roll, pitch, yaw), default is radians, but set
# degrees true if giving degrees
q = Quaternion.from_euler(0, -90, 100, degrees=True)

# can get the euler angles back out in degrees (set to True)
e = q.to_euler(degrees=True)
d = q.to_dict()

# iterate through values
for i in q:
print(f"{i}")

# indexing like a namedtuple
z = q[3]
z = q[-1]
v = q[-3:]
w = q[0]

# class properties
v = q.vector     # returns a tuple (x,y,z)
s = q.scalar     # returns a double (w)
n = q.normalize  # returns unit quaternion
m = q.magnitude  # returns the magnitude of the quaternion
a = q.angle      # returns angle of rotation in radians
a = q.axis       # returns axis of rotation

# useful attr functions
q == q    # compare will return True
q != q    # will return False
print(q)  # pretty print
w = q.w
x = q.x
y = q.y
z = q.z```