How to use JointStatesFromTraj() & JointStateFromTraj()

[DavidB-CMU]

What is the difference between these two functions, and how do I use them?

prpy.util.JointStatesFromTraj()
prpy.util.JointStateFromTraj()

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For example, I have a timed trajectory.

waypoint idx 10 has delta_time = 0.578625550278

Extracting waypoint 10 gives me 15 values, including position and velocity:

[ 4.72509056 -0.80361648 -0.40874884 1.62480367 -0.44666198 -0.80896596
-2.5743101 -0.19636848 0.20038932 -0.25245062 -0.74623971 -0.61489159
0.65293156 1. 0.04002589]

Then JointStatesFromTraj() for waypoint idx 10 gives me this:

pva_list[10] = [array([ 0. , 0. , 0. , 0. , 0. ,
0. , 0. , 0. , 0. , 0. ,
0. , 0. , 0. , 0. , 0. ,
4.74008604, 0. , -0.82155363, 0. , -0.42307695,
1.58725633, -0.43116916, -0.82954712, -2.57900286, 0. , 0. ]), array([ 0. , 0. , 0. , 0. , 0. ,
0. , 0. , 0. , 0. , 0. ,
0. , 0. , 0. , 0. , 0. ,
-0.09723434, 0. , 0.15674668, 0. , -0.27341786,
-0.8 , -0.47945874, 0.57077024, 0.8395961 , 0. , 0. ]), None]

containing two arrays of 26 values and the 3rd empty.
There's a lot of zeros in there.

.

The docstring for JointStateFromTraj() is the same as JointStatesFromTraj(), so I don't know what it's supposed to be doing.
Calling JointStateFromTraj() on my trajectory returns

ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all()