Box & Violin Plots

Purpose

Box plots and violin plots compare distributions across groups. They highlight:

• Median and quartiles (box plot).
• Full distribution shape (violin plot).
• Outliers and range.

Example in the Notebook

The notebook displays total bill by day using:

1. A box plot (left panel) — shows median, IQR, whiskers, and outliers.
2. A violin plot (right panel) — shows the full distribution shape.
3. An overlaid swarm plot (right panel) — individual data points.

Key Code Snippet

sns.boxplot(data=tips, x='day', y='total_bill', hue='day', dodge=False, ax=axes[0], palette='pastel')
sns.violinplot(data=tips, x='day', y='total_bill', hue='day', split=False, inner=None, ax=axes[1], palette='muted')
sns.swarmplot(data=tips, x='day', y='total_bill', color='k', size=3, ax=axes[1])

Customization Tips

• Boxplot parts: Show quartiles, mean, or whiskers with showmeans=True, showfliers=True.
• Violin plot shape: Use split=True to compare two hue groups side-by-side (for 2-level categorical).
• Inner representation: Set inner='box', inner='quartile', or inner=None (violin only).
• Point overlay: Add sns.swarmplot() or sns.stripplot() for individual observations.
• Orient: Use orient='h' for horizontal layout.

When to Use

• Box plots: quick comparison of medians and spreads across many groups.
• Violin plots: when distribution shape matters more than individual points.
• Swarm overlay: when sample size is small (< 50 per group) and you want to see all points.

See Also

• Seaborn: boxplot(), violinplot(), swarmplot()