Source code for geometry.basic_utils

import warnings

from contracts import contract, new_contract
import numpy as np

from .constants import GeometryConstants

new_contract('R1', 'array[1]')
new_contract('R2', 'array[2]')
new_contract('R3', 'array[3]')

try:

    @new_contract
    @contract(x='array')
    def finite(x):
        # TODO: make into standard thing
        return np.isfinite(x).all()

except:
    pass


@contract(s='array')
def normalize_length(s, norm=2):
    ''' Normalize an array such that it has unit length in the given norm. '''
    sn = np.linalg.norm(s, norm)
    if np.allclose(sn, 0, atol=GeometryConstants.atol_zero_norm):
        raise ValueError('Norm is zero')
    else:
        return s / sn


@contract(s='array')
def normalize_length_or_zero(s, norm=2):
    '''
        Normalize an array such that it has unit length in the given norm;
        if the norm is close to zero, the zero vector is returned.
    '''
    sn = np.linalg.norm(s, norm)
    if np.allclose(sn, 0, atol=GeometryConstants.atol_zero_norm):
        return s
    else:
        return s / sn


def deprecated(func):
    """This is a decorator which can be used to mark functions
    as deprecated. It will result in a warning being emitted
    when the function is used."""

    def new_func(*args, **kwargs):
        warnings.warn("Call to deprecated function %s." % func.__name__,
                      category=DeprecationWarning, stacklevel=2)
        return func(*args, **kwargs)

    new_func.__name__ = func.__name__
    new_func.__doc__ = func.__doc__
    new_func.__dict__.update(func.__dict__)
    return new_func


def safe_arccos(x):
    '''
        Returns the arcosine of x, clipped between -1 and 1.

        Use this when you know x is a cosine, but it might be
        slightly over 1 or below -1 due to numerical errors.
    '''
    return np.arccos(np.clip(x, -1.0, 1.0))