v2.15.0

This release adds angular dimensions, dimensions along one component, and convex hulls. The ESIS instrument paper needs all three to draw the schematic of its optical system.

Angular dimensions

na.plt.dimension_angular() is the counterpart of na.plt.dimension() for angles (#269):

• Arc: it draws an arc around a vertex, from one direction to another, with an arrowhead at each end.
• Extension lines: they join each end of the arc back towards the vertex. They start a gap beyond radius_inner, so they can begin at the edge of the part whose angle is being dimensioned.
• Label: it defaults to the size of the angle in degrees. Angles without units are in radians.
• Arrowheads: they take every property of the arc that an arrow has, like its color and line width, and its zorder.

Dimensions along one component

na.plt.dimension(..., along="x") dimensions only the distance along one plotted component (#269). A mechanical drawing does the same for the horizontal or vertical distance between two features that are not level with each other.

• Dimension line: it is parallel to that component, offset from a.
• Extension lines: each point is joined to the dimension line by an extension line of its own length.
• Gap: the gap before each extension line is the same at both points. It is a fraction of the longer extension line, and never longer than the line it starts.

Both functions now replace matplotlib's aliases, like c and lw, with the names they stand for before merging them with their defaults. So aliases replace the defaults rather than conflicting with them.

Behavior changes in na.plt.dimension():

• A distance of zero raises a ValueError, where it used to draw lines of NaN.
• A gap greater than 1 gives extension lines of zero length. They used to start beyond the dimension line and run back to it.

Convex hulls

na.geometry.convex_hull(points, axis, axis_vertex="vertex", where=True) reduces the points along axis to the vertices of their convex hull, along the new axis axis_vertex (#270).

• Batches: every other axis is a batch axis, and each set of points gets a hull of its own. Each hull is found with Andrew's monotone chain in a Numba kernel, which runs in parallel over the sets.
• Order: the vertices run counterclockwise from the one with the least x, or the least y among a tie.
• Padding: each hull is padded to the size of the largest by repeating its last vertex, which leaves the polygon unchanged.
• Selection: where picks which points take part, such as the rays that are not vignetted. Points with a coordinate that isn't finite are left out.
• Degenerate sets:
  • Points on an edge are not vertices, and neither are copies of a vertex.
  • Collinear points have a hull of their two ends.
  • Coincident points have a hull of one vertex.
  • A set with no points has a hull of NaN.
• Units and types: the vertices keep the unit of the x-coordinates and the floating-point type of the points.
• Inputs: the points must be a vector with exactly the components x and y. Uncertain points are not supported yet, and raise a TypeError.

Full Changelog: v2.14.1...v2.15.0