grains.geometry.is_collinear

grains.geometry.is_collinear(points, tol=None)[source]

Decides whether a set of points is collinear.

Works in any dimensions.

Parameters

  • points (ndarray) – 2D numpy array with N columns, each row corresponding to a point, and the N columns giving the Cartesian coordinates of the point.

  • tol (float, optional) – Tolerance value passed to numpy’s matrix_rank function. This tolerance gives the threshold below which SVD values are considered zero.

Returns

bool – True for collinear points.

See also

numpy.linalg.matrix_rank()

Notes

The algorithm for three points is from Tim Davis.

Examples

Two points are always collinear

>>> is_collinear(np.array([[1, 0], [1, 5]]))
True

Three points in 3D which are supposed to be collinear (returns false due to numerical error)

>>> is_collinear(np.array([[0, 0, 0], [1, 1, 1], [5, 5, 5]]), tol=0)
False

The previous example with looser tolerance

>>> is_collinear(np.array([[0, 0, 0], [1, 1, 1], [5, 5, 5]]), tol=1e-14)
True