When comparing products year over year, a slopegraph connects two time points with lines. It conveys rank and change size at the same time.
import matplotlib.pyplot as plt
import numpy as np
brands = ["Service A", "Service B", "Service C", "Service D", "Service E"]
score_2023 = np.array([62, 55, 48, 44, 38])
score_2024 = np.array([75, 58, 64, 40, 42])
colors = plt.cm.Blues(np.linspace(0.4, 0.8, len(brands)))
fig, ax = plt.subplots(figsize=(6, 4))
for idx, name in enumerate(brands):
ax.plot(
[0, 1],
[score_2023[idx], score_2024[idx]],
color=colors[idx],
linewidth=2.5,
)
ax.scatter([0, 1], [score_2023[idx], score_2024[idx]], color=colors[idx], s=60)
ax.text(
-0.05,
score_2023[idx],
f"{name} {score_2023[idx]:.0f}",
ha="right",
va="center",
)
ax.text(
1.05,
score_2024[idx],
f"{score_2024[idx]:.0f}",
ha="left",
va="center",
)
ax.set_xticks([0, 1], labels=["2023", "2024"])
ax.set_title("NPS change for key services (points)")
ax.set_ylim(30, 80)
ax.spines[["top", "right", "bottom"]].set_visible(False)
ax.tick_params(left=False, bottom=False)
ax.set_yticks([])
ax.grid(axis="y", alpha=0.15)
fig.tight_layout()
plt.show()

Reading tips #
- Height shows the score at each time point; slope shows growth or decline.
- Crossing lines indicate rank reversals, worth highlighting in commentary.
- Sorting by change size can emphasize movement.