# Quaternion transformations in Python

I'm trying to place some Markers in RViz, using a node written in Python. To this end, I need to create a `geometry_msgs.mgs.Pose`

with an `orientation`

Quaternion.

But I can't for the life of me find the utility and conversion functions that I need for Quaternions. There are *some* in `tf.transformations`

, but those produce `numpy`

Quaternions, which I would have to manually split up and throw into the `geometry_msgs.msg.Quaternion`

constructor.

Considering that Quaternions are of little use without a set of functions to work with them, my question is: **Where are the proper conversion functions for Quaternions?** That is, functions to create and modify `geometry_msgs.msg.Quaternion`

or to convert between a `numpy`

Quaternion (4-tuple) and `geometry_msgs.msg.Quaternion`

(object with x,y,z,w attributes).

My environment is Ubuntu 12.04 Precise, with ROS fuerte (using fuerte is currently mandatory for this project; I'm already looking into upgrading, but that's not at all easy).