Many groups sharing one outer edge share one margin

Every column here is its own two-panel group, and every one of them has a title_position="top" title touching the grid’s own top edge – eight groups sharing that single edge, not eight interior ones the way the earlier “many small groups” example mostly used. tight_layout() still reserves just one band across the top, sized for the single largest title reaching it, exactly as if there were only one group there: the eight groups sit side by side along that shared edge, so the band never needs to be taller than whichever one of them needs the most room, no matter how many columns share it.

Interior row-pair boundaries are a different story – as the earlier examples show, those need their own explicit group_spacing(hspace=...) room, since no title faces them at all.

This figure has 16 panels — too many to usefully embed at a fixed size.

Open the full interactive example in a new page to pick a tool, then zoom, pan, point-pick or annotate any panel.

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import numpy as np
import plotpress

rng = np.random.default_rng(11)
nrows, ncols = 2, 8
x = np.linspace(0, 6, 13)
y = np.linspace(0, 6, 13)
X, Y = np.meshgrid(x, y)

fig, axes = plotpress.subplots(nrows, ncols, figsize=(16, 4.5))

for col in range(ncols):
    top_ax, bot_ax = axes[0, col], axes[1, col]
    Z = np.sin(X + 0.4 * col) * np.cos(Y - 0.3 * col)
    top_ax.pcolormesh(x, y, Z, cmap="viridis", vmin=-1, vmax=1)
    bot_ax.pcolormesh(x, y, -Z, cmap="viridis", vmin=-1, vmax=1)
    top_ax.set_title("+", fontsize=8)
    bot_ax.set_title("−", fontsize=8)
    top_ax.tick_params(labelsize=5)
    bot_ax.tick_params(labelsize=5)
    fig.group(f"Col {col}", [top_ax, bot_ax], title_position="top",
             pad=4.0, linewidth=1.0)

fig.group_spacing(wspace=10.0)
fig.tight_layout()