Annotated Line Plot with Event Markers — Seaborn

A line plot with annotations at key points marking important events or milestones. This visualization enhances time series data by highlighting significant occurrences such as product launches, policy changes, or market events directly on the chart. Vertical lines, markers, and text labels draw attention to specific moments in time, making it easy to correlate data trends with real-world events.

Annotated Line Plot with Event Markers rendered with Seaborn

Python source (Seaborn)

""" anyplot.ai
line-annotated-events: Annotated Line Plot with Event Markers
Library: seaborn 0.13.2 | Python 3.13.13
Quality: 91/100 | Updated: 2026-05-16
"""

import os

import matplotlib.pyplot as plt
import numpy as np
import pandas as pd
import seaborn as sns
from matplotlib.lines import Line2D


# Theme tokens
THEME = os.getenv("ANYPLOT_THEME", "light")
PAGE_BG = "#FAF8F1" if THEME == "light" else "#1A1A17"
ELEVATED_BG = "#FFFDF6" if THEME == "light" else "#242420"
INK = "#1A1A17" if THEME == "light" else "#F0EFE8"
INK_SOFT = "#4A4A44" if THEME == "light" else "#B8B7B0"

# Okabe-Ito palette
BRAND = "#009E73"  # Position 1 - bluish green for main series
EVENT_COLOR = "#954477"  # Position 7 - yellow for annotations

# Configure seaborn with theme tokens
sns.set_theme(
    style="ticks",
    rc={
        "figure.facecolor": PAGE_BG,
        "axes.facecolor": PAGE_BG,
        "axes.edgecolor": INK_SOFT,
        "axes.labelcolor": INK,
        "text.color": INK,
        "xtick.color": INK_SOFT,
        "ytick.color": INK_SOFT,
        "grid.color": INK,
        "grid.alpha": 0.10,
        "legend.facecolor": ELEVATED_BG,
        "legend.edgecolor": INK_SOFT,
    },
)

# Data - Simulating monthly product sales with marketing events
np.random.seed(42)

# Create 365 days of sales data
dates = pd.date_range("2024-01-01", periods=365, freq="D")
# Base trend with seasonality and noise
trend = np.linspace(100, 180, 365)
seasonality = 15 * np.sin(np.linspace(0, 4 * np.pi, 365))
noise = np.random.normal(0, 8, 365)
sales = trend + seasonality + noise

df = pd.DataFrame({"date": dates, "sales": sales})

# Events - Key marketing milestones
events = pd.DataFrame(
    {
        "event_date": pd.to_datetime(["2024-02-14", "2024-05-01", "2024-07-15", "2024-09-20", "2024-11-25"]),
        "event_label": ["Valentine's Campaign", "Spring Sale", "Summer Launch", "Fall Promotion", "Black Friday"],
    }
)

# Plot
fig, ax = plt.subplots(figsize=(16, 9), facecolor=PAGE_BG)

# Main line plot using seaborn
sns.lineplot(data=df, x="date", y="sales", ax=ax, linewidth=2.5, color=BRAND)

# Add event markers with alternating heights for readability
y_positions = [0.85, 0.75, 0.85, 0.75, 0.85]

for i, (_, event) in enumerate(events.iterrows()):
    # Vertical line at event date
    ax.axvline(x=event["event_date"], color=EVENT_COLOR, linestyle="--", linewidth=2, alpha=0.8)

    # Event label with background
    y_pos = ax.get_ylim()[0] + (ax.get_ylim()[1] - ax.get_ylim()[0]) * y_positions[i]
    ax.annotate(
        event["event_label"],
        xy=(event["event_date"], y_pos),
        fontsize=14,
        fontweight="bold",
        color=INK,
        ha="center",
        va="bottom",
        bbox={"boxstyle": "round,pad=0.3", "facecolor": EVENT_COLOR, "edgecolor": "none", "alpha": 0.9},
        rotation=0,
    )

    # Small marker on the line at event date
    event_sales = df.loc[df["date"] == event["event_date"], "sales"]
    if not event_sales.empty:
        ax.scatter(
            event["event_date"], event_sales.values[0], color=EVENT_COLOR, s=150, zorder=5, edgecolor=INK, linewidth=2
        )

# Styling
ax.set_xlabel("Date", fontsize=20, color=INK)
ax.set_ylabel("Daily Sales (Units)", fontsize=20, color=INK)
ax.set_title("line-annotated-events · seaborn · anyplot.ai", fontsize=24, fontweight="medium", color=INK)
ax.tick_params(axis="both", labelsize=16, colors=INK_SOFT)

# Remove top and right spines
ax.spines["top"].set_visible(False)
ax.spines["right"].set_visible(False)
for spine in ["left", "bottom"]:
    ax.spines[spine].set_color(INK_SOFT)

# Subtle y-axis grid
ax.yaxis.grid(True, alpha=0.10, linewidth=0.8, color=INK)

# Add legend explaining event markers
legend_elements = [
    Line2D([0], [0], color=BRAND, lw=2.5, label="Daily Sales"),
    Line2D([0], [0], color=EVENT_COLOR, lw=2, linestyle="--", label="Event Marker"),
]
ax.legend(handles=legend_elements, loc="upper left", fontsize=16, frameon=True, fancybox=True)

# Format x-axis dates
fig.autofmt_xdate(rotation=30)

plt.tight_layout()
plt.savefig(f"plot-{THEME}.png", dpi=300, bbox_inches="tight", facecolor=PAGE_BG)

Part of Annotated Line Plot with Event Markers on anyplot.ai.

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