plot_nested_arrow.py

"""
Figure 1 from the thesis:
Schematic nested simulation diagram with arrows showing outer and inner scenarios.
"""

import matplotlib.pyplot as plt
import matplotlib.patches as mpatches

fig, ax = plt.subplots(figsize=(8, 5))
ax.set_xlim(0, 1)
ax.set_ylim(0, 1)
ax.axis('off')

# Time labels
ax.text(0.1, 0.02, 't=0', ha='center', fontsize=11, fontweight='bold')
ax.text(0.4, 0.02, r'$T_0$', ha='center', fontsize=11, fontweight='bold')
ax.text(0.8, 0.02, r'$T_1$', ha='center', fontsize=11, fontweight='bold')

# Labels
ax.text(0.15, 0.95, 'outer scenarios', ha='center', fontsize=10)
ax.text(0.55, 0.95, 'inner scenarios', ha='center', fontsize=10)

# Outer scenarios: from (0.1, 0.5) to 3 endpoints at T0
x_start = 0.1
x_mid = 0.4
x_end = 0.8
y_center = 0.5
outer_y = [0.8, 0.5, 0.2]

arrow_props = dict(arrowstyle='->', lw=1.5, color='black')

for y in outer_y:
    ax.annotate('', xy=(x_mid, y), xytext=(x_start, y_center),
                arrowprops=arrow_props)

# Inner scenarios: from each T0 endpoint to 3 endpoints at T1
inner_offsets = [0.1, 0.0, -0.1]

for y_mid in outer_y:
    for dy in inner_offsets:
        y_end = y_mid + dy
        y_end = max(0.05, min(0.95, y_end))
        ax.annotate('', xy=(x_end, y_end), xytext=(x_mid, y_mid),
                    arrowprops=arrow_props)

# Dots at nodes
ax.plot(x_start, y_center, 'ko', markersize=5)
for y in outer_y:
    ax.plot(x_mid, y, 'ko', markersize=5)

fig.tight_layout()
fig.savefig('plot_nested_arrow.png', dpi=150)
print("Saved: plot_nested_arrow.png")

plt.show()