"""
Nested groups
=============

``fig.group()`` has no notion of nesting or hierarchy -- it always draws one
box, sized to the bounding rectangle of whichever axes it was given. This
figure *looks* nested (an outer "All four" box visually containing two
narrower ones, titles included) purely because that is what its own box
happens to bound: within a plain 2x2 grid, ``Left pair``/``Right pair``
each group one 2x1 column, and ``All four`` separately groups all four
axes. All three are otherwise completely independent, unrelated groups as
far as plotpress is concerned -- nothing links ``All four`` to the two
narrower ones, or stops you from moving one axes out of a "child" group
without touching the "parent" at all.

Two choices make every title land *inside* the outer box rather than
alongside or past it:

- ``Left pair``/``Right pair`` take the one edge each actually reaches
  that the other doesn't (``left``/``right``); ``All four`` takes
  ``bottom``, the one edge neither of them uses -- ``tight_layout()``
  reserves title space per *edge*, not per group, so distinct edges avoid
  two titles fighting over one reservation.
- Margins are set by hand with :meth:`~plotpress.figure.Figure.subplots_adjust`
  instead of :meth:`~plotpress.figure.Figure.tight_layout`. ``All four``'s
  own ``pad`` has to be wide enough to clear ``Left pair``'s and
  ``Right pair``'s *titles*, not just their axes -- room ``tight_layout()``
  never reserves on its own, since neither of those titles faces a figure
  edge it knows to budget for. Generous, explicit margins on every side
  give that pad somewhere to expand into without running off the canvas.
"""
import numpy as np
import plotpress

rng = np.random.default_rng(9)
x = np.linspace(0, 6, 13)
y = np.linspace(0, 6, 13)
X, Y = np.meshgrid(x, y)

fig, axes = plotpress.subplots(2, 2, figsize=(9, 8))
for r in range(2):
    for c in range(2):
        Z = np.sin(X * 0.6 + r) * np.cos(Y * 0.6 + c) + 0.05 * rng.standard_normal(X.shape)
        axes[r, c].pcolormesh(x, y, Z, cmap="cividis", vmin=-1.2, vmax=1.2)
        axes[r, c].tick_params(labelsize=6)

fig.group("Left pair", [axes[0, 0], axes[1, 0]], title_position="left", color="#2ca02c")
fig.group("Right pair", [axes[0, 1], axes[1, 1]], title_position="right", color="#9467bd")
fig.group("All four", list(axes.ravel()), title_position="bottom", color="black",
         pad=75.0)
fig.subplots_adjust(left=0.20, right=0.80, top=0.90, bottom=0.16,
                    wspace=0.30, hspace=0.30)