Source code for irfpy.spice.geometric_finder

""" Emulate the gf

It is not straightforward to use GF functionality.
Here is a "simplified" version.

It is crude implementation, so it could be much slower...
"""
import numpy as np

#from irfpy.util.timeinterval import timeinterval
from irfpy.util import span, utc
from irfpy.spice import spicetools as _s

def distance_below(target, origin, distance, initaial_interval, dt, correction='NONE', frame='J2000'):
    """ Return the time interval where (Target - Origin) distance is <=distance.

    :param target: Target body
    :param origin: Origin body
    :param distance: Threshold distance
    :param initial_interval:
        Initial time interval. See sample below.
    :type initaial_interval: :class:`irfpy.util.timeinterval.timeinterval`.
    :param dt: Time resolution to search for.
    :keyword correction: Abberation correction.
    :keyword frame: Frame to calculate. The distance should not depend on the selection
        of the frame, but still user may allow to set it.
    :return: Time interval that satisfy the condition.
    :rtype: :class:`irfpy.util.timeinterval.timeinterval` object.

    The time interval can be specified as follows.

    >>> from irfpy.util.timeinterval import timeinterval
    >>> import datetime
    >>> t0 = datetime.datetime(2010, 1, 3, 12, 0, 0)
    >>> t1 = datetime.datetime(2010, 1, 3, 13, 0, 0)
    >>> tint = timeinterval(t0, t1)     # Between t0 and t1

    The returned value is also for in the :class:`irfpy.util.timeinterval.timeinterval` object.
    """

    ### Very crude implementation so far
    tlist = initaial_interval.sampling(dt)    # Time interval is sampled by dt.

    distlist = np.array([_s.get_distance(t, target, origin, frame=frame, correction=correction) for t in tlist])
    
    nearlist = np.where(distlist <= distance, True, False)
    
    interval = span.timearray2interval(nearlist, tlist)
    
    return interval