"""
Many small groups: pairing every other row
=============================================

A 6x5 grid of ``pcolormesh`` panels (30 total), split into fifteen small
two-panel groups -- each pairing a row with the one directly below it in
the same column: rows 0/1, 2/3, and 4/5. Every group gets its own title, so
which panel goes with which reads at a glance instead of needing a caption.

Only the *first* row-pair of each column touches the grid's own top edge,
so only those five groups get an automatic ``tight_layout()`` margin for
their titles (see the previous two examples); the other ten groups are
interior and would have their titles collide with the row above unless the
grid itself has enough vertical breathing room between rows to begin with.
Column-adjacent groups (one site next to another) are packed just as
tightly, so this needs both directions: ``group_spacing(wspace=...,
hspace=...)`` reserves that room explicitly, on top of whatever
``tight_layout()`` already fit from tick/axis decorations alone -- it knows
nothing about a group's own title, which is exactly what this adds.
"""
import numpy as np
import plotpress

rng = np.random.default_rng(4)
nrows, ncols = 6, 5
n_sites, n_scans = ncols, nrows // 2
x = np.linspace(0, 8, 17)
y = np.linspace(0, 4, 9)
X, Y = np.meshgrid(x, y)

fig, axes = plotpress.subplots(nrows, ncols, figsize=(14, 13))

for site in range(n_sites):
    phase = 0.4 * site
    for scan in range(n_scans):
        top_ax, bot_ax = axes[scan * 2, site], axes[scan * 2 + 1, site]
        base = np.sin(X - phase - scan) * np.cos(Y * 0.6)
        raw = base + 0.08 * rng.standard_normal(X.shape)
        top_ax.pcolormesh(x, y, raw, cmap="viridis", vmin=-1.2, vmax=1.2)
        bot_ax.pcolormesh(x, y, base, cmap="viridis", vmin=-1.2, vmax=1.2)
        top_ax.set_title("raw", fontsize=7)
        bot_ax.set_title("smoothed", fontsize=7)
        top_ax.tick_params(labelsize=5)
        bot_ax.tick_params(labelsize=5)
        fig.group(f"Site {site + 1} - Scan {scan + 1}", [top_ax, bot_ax],
                 title_position="top", pad=4.0, linewidth=1.0)

fig.group_spacing(wspace=18.0, hspace=65.0)
fig.tight_layout()