choose_minor_divider

pysmithchart.utils.choose_minor_divider(p0, p1, candidates, threshold, map_func, *, max_divisions=None, prefer_aligned=True, prefer_nice=True, tol=1e-09)[source]

Choose a minor-grid divider that yields visually acceptable spacing.

This is the shared algorithm used by both fancy and non-fancy minor grids.

The divider is selected from candidates by testing each candidate divider d via the minimum adjacent distance in mapped (Moebius) space over the entire interval [p0, p1]. Candidates that do not meet threshold are rejected.

Among acceptable candidates, the selection prefers:

  1. aligned endpoints (both endpoints are integer multiples of the implied step),

  2. “nice” decimal steps (mantissas in {1, 2, 2.5, 5} × 10^n),

  3. larger divider counts.

Parameters:

  • p0 – Interval endpoint

  • p1 – Interval endpoint, with p1 > p0.

  • candidates – Iterable of integer candidate division counts (e.g. [1, 2, 3, 4, 5, 10]).

  • threshold – Minimum acceptable adjacent spacing in mapped space.

  • map_func – Callable map_func(p) -> complex mapping a parameter value to a complex coordinate (e.g., Moebius-space point).

  • max_divisions – If provided, ignore candidates greater than this value.

  • prefer_aligned – If True, prefer candidates where both endpoints are close to integer multiples of the implied step.

  • prefer_nice – If True, prefer “nice” decimal steps (mantissas in {1, 2, 2.5, 5}×10^n).

  • tol – Tolerance used for alignment checks.

Returns:

int – Chosen division count. Falls back to the smallest candidate if none satisfy the threshold.