timeseries.SpaceCurve.reparam

SpaceCurve.reparam(rate)

Change time parametrization, to represent a constant change of speed. Locations, initial time, and arc-length are preserved.

Parameters:

rate : float

A (positive) ratio by which to increase the speed.

Notes

If speed[i] changes to speed[i]*q[i], then delta_t[i] changes to delta_t[i]*p[i], where p[i] = 1 / q[i].

Examples

>>> tn = np.arange(0, 5*1e9, 1e9)
>>> s = SpaceCurve(tn=tn, px=10.0*tn/1e9) # drive straight at 10m/s
>>> s
SpaceCurve with 5 entries and duration 4.000000000
>>> s.data
            time  pos_x  pos_y  pos_z  quality
0            0.0    0.0    0.0    0.0       -1
1000000000   1.0   10.0    0.0    0.0       -1
2000000000   2.0   20.0    0.0    0.0       -1
3000000000   3.0   30.0    0.0    0.0       -1
4000000000   4.0   40.0    0.0    0.0       -1
>>> a = s.reparam(0.5)
>>> a.data
            time  pos_x  pos_y  pos_z  quality
0            0.0    0.0    0.0    0.0       -1
2000000000   2.0   10.0    0.0    0.0       -1
4000000000   4.0   20.0    0.0    0.0       -1
6000000000   6.0   30.0    0.0    0.0       -1
8000000000   8.0   40.0    0.0    0.0       -1
>>> a
SpaceCurve with 5 entries and duration 8.000000000
>>> b = s.reparam(2.0) 
>>> b
SpaceCurve with 5 entries and duration 2.000000000
>>> b.data
            time  pos_x  pos_y  pos_z  quality
0            0.0    0.0    0.0    0.0       -1
500000000    0.5   10.0    0.0    0.0       -1
1000000000   1.0   20.0    0.0    0.0       -1
1500000000   1.5   30.0    0.0    0.0       -1
2000000000   2.0   40.0    0.0    0.0       -1