Overlapping Histograms — Matplotlib

Overlapping histograms display multiple distributions on the same axes using semi-transparent bars, enabling direct visual comparison between groups. This technique reveals differences in central tendency, spread, and shape across categories while maintaining the familiar histogram format. The transparency allows viewers to see where distributions overlap and diverge.

Overlapping Histograms rendered with Matplotlib

Python source (Matplotlib)

""" anyplot.ai
histogram-overlapping: Overlapping Histograms
Library: matplotlib 3.10.9 | Python 3.13.13
Quality: 90/100 | Updated: 2026-05-08
"""

import os

import matplotlib.pyplot as plt
import numpy as np


# 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 colors (first series is always #009E73)
IMPRINT = ["#009E73", "#C475FD", "#4467A3"]

# Data - Comparing salary distributions across three departments
np.random.seed(42)

# Engineering: higher salaries, tighter distribution
engineering = np.random.normal(95000, 12000, 200)

# Marketing: moderate salaries, wider spread
marketing = np.random.normal(75000, 18000, 180)

# Sales: lower base but high variance due to commissions
sales = np.random.normal(65000, 22000, 220)

# Create plot
fig, ax = plt.subplots(figsize=(16, 9), facecolor=PAGE_BG)
ax.set_facecolor(PAGE_BG)

# Define consistent bins for all groups
bins = np.linspace(20000, 150000, 35)

# Plot overlapping histograms with transparency
ax.hist(engineering, bins=bins, alpha=0.5, label="Engineering", color=IMPRINT[0], edgecolor=INK_SOFT, linewidth=1.5)
ax.hist(marketing, bins=bins, alpha=0.5, label="Marketing", color=IMPRINT[1], edgecolor=INK_SOFT, linewidth=1.5)
ax.hist(sales, bins=bins, alpha=0.5, label="Sales", color=IMPRINT[2], edgecolor=INK_SOFT, linewidth=1.5)

# Labels and styling
ax.set_xlabel("Annual Salary ($)", fontsize=20, color=INK)
ax.set_ylabel("Number of Employees", fontsize=20, color=INK)
ax.set_title("histogram-overlapping · matplotlib · anyplot.ai", fontsize=24, fontweight="medium", color=INK)
ax.tick_params(axis="both", labelsize=16, colors=INK_SOFT)

# Grid - subtle on both axes
ax.grid(True, alpha=0.10, linewidth=0.8, color=INK)
ax.set_axisbelow(True)

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

# Format x-axis with thousands separator
ax.xaxis.set_major_formatter(plt.FuncFormatter(lambda x, p: f"{x / 1000:.0f}k"))

# Legend styling
leg = ax.legend(fontsize=16, loc="upper right")
if leg:
    leg.get_frame().set_facecolor(ELEVATED_BG)
    leg.get_frame().set_edgecolor(INK_SOFT)
    leg.get_frame().set_linewidth(0.8)
    plt.setp(leg.get_texts(), color=INK_SOFT)

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

Part of Overlapping Histograms on anyplot.ai.

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