Side-by-side groups with left/right titles

Two groups need not stack (as the row-based “Temperature sweep”/”Pressure sweep” example does) – they can sit side by side instead, each labeled on the outer edge it actually touches: title_position="left" for the left half of the grid, "right" for the right half. Both reach a true outer edge of the figure, so tight_layout() reserves margin for each independently, on its own side.

The boundary between the two halves (column 1 / column 2) is interior, though, and neither title faces it – “Before“‘s box still needs room for its own tick labels beyond its bare axes on that side, and “After“‘s box needs the same on its side, so left at tight_layout()’s default column spacing the two collided right at that seam. group_spacing(wspace=...) widens every column gap explicitly instead, interior boundary included – without giving up tight_layout()’s own automatic margins the way subplots_adjust would.

This figure has 8 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(7)
x = np.linspace(0, 10, 21)
y = np.linspace(0, 6, 13)
X, Y = np.meshgrid(x, y)

fig, axes = plotpress.subplots(2, 4, figsize=(12, 5.5))
flat = axes.ravel()
for i, ax in enumerate(flat):
    row, col = i // 4, i % 4
    noise = 0.5 if col < 2 else 0.1   # left half noisier ("before"), right cleaner ("after")
    Z = np.sin(X * 0.6 + row) * np.cos(Y * 0.5) + noise * rng.standard_normal(X.shape)
    ax.pcolormesh(x, y, Z, cmap="coolwarm", vmin=-1.5, vmax=1.5)
    ax.set_title(f"Run {i}", fontsize=8)
    ax.tick_params(labelsize=6)

fig.group("Before", list(flat[[0, 1, 4, 5]]), color="#7f7f7f", linestyle="--",
         title_position="left")
fig.group("After", list(flat[[2, 3, 6, 7]]), color="#2ca02c", linestyle="--",
         title_position="right")
fig.group_spacing(wspace=16.0)
fig.tight_layout()