Seaborn Statistical Visualization

Overview

Seaborn is a Python visualization library for creating publication-quality statistical graphics. Use this skill for dataset-oriented plotting, multivariate analysis, automatic statistical estimation, and complex multi-panel figures with minimal code.

Environment and Installation

Current upstream documentation is for seaborn 0.13.2. Official docs support Python 3.8+ with mandatory NumPy, pandas, and matplotlib dependencies; scipy, statsmodels, and fastcluster are optional for some advanced statistics and clustering workflows.

# Reproducible install for examples in this skill
uv pip install "seaborn==0.13.2"

# Include optional statistical dependencies when needed
uv pip install "seaborn[stats]==0.13.2"

Recommended imports:

import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
import seaborn as sns
import seaborn.objects as so

sns.load_dataset() downloads public example data when it is not cached. For private, regulated, or offline work, load local files explicitly with pandas and pass the resulting DataFrame to seaborn.

Design Philosophy

Seaborn follows these core principles:

1. Dataset-oriented: Work directly with DataFrames and named variables rather than abstract coordinates
2. Semantic mapping: Automatically translate data values into visual properties (colors, sizes, styles)
3. Statistical awareness: Built-in aggregation, error estimation, and confidence intervals
4. Aesthetic defaults: Publication-ready themes and color palettes out of the box
5. Matplotlib integration: Full compatibility with matplotlib customization when needed

Quick Start

import seaborn as sns
import matplotlib.pyplot as plt
import pandas as pd

# Load example dataset
df = sns.load_dataset('tips')

# Create a simple visualization
sns.scatterplot(data=df, x='total_bill', y='tip', hue='day')
plt.show()

Core Plotting Interfaces

Function Interface (Traditional)

The function interface provides specialized plotting functions organized by visualization type. Each category has axes-level functions (plot to single axes) and figure-level functions (manage entire figure with faceting).

When to use:

• Quick exploratory analysis
• Single-purpose visualizations
• When you need a specific plot type

Objects Interface (Modern)

The seaborn.objects interface provides a declarative, composable API similar to ggplot2. Build visualizations by chaining methods to specify data mappings, marks, transformations, and scales. Upstream still describes this interface as experimental and incomplete in 0.13.2, although stable enough for serious use; prefer the function interface for conservative production code unless the compositional API materially simplifies the plot.

When to use:

• Complex layered visualizations
• When you need fine-grained control over transformations
• Building custom plot types
• Programmatic plot generation

from seaborn import objects as so

# Declarative syntax
(
    so.Plot(data=df, x='total_bill', y='tip')
    .add(so.Dot(), color='day')
    .add(so.Line(), so.PolyFit())
)

Current API Notes

Seaborn 0.12 and 0.13 changed several common plotting patterns:

• Most plotting functions now require keyword arguments for variables. Prefer sns.scatterplot(data=df, x="x", y="y") over positional sns.scatterplot(df["x"], df["y"]).
• errorbar replaces the old ci parameter in lineplot(), barplot(), and pointplot(). Regression functions such as regplot() and lmplot() still use ci.
• Categorical plots were rewritten in 0.13. Use native_scale=True when numeric or datetime categories should keep their original scale instead of ordinal positions.
• Passing palette without assigning hue is deprecated for categorical functions. If each category should get its own color, assign a redundant hue such as hue="day" and set legend=False.
• Prefer renamed parameters: violinplot(density_norm=..., common_norm=...) instead of scale/scale_hue, boxenplot(width_method=...) instead of scale, and barplot(err_kws=...) instead of errcolor/errwidth.

Plotting Functions by Category

Relational Plots (Relationships Between Variables)

Use for: Exploring how two or more variables relate to each other

• scatterplot() - Display individual observations as points
• lineplot() - Show trends and changes (automatically aggregates and computes CI)
• relplot() - Figure-level interface with automatic faceting

Key parameters:

• x, y - Primary variables
• hue - Color encoding for additional categorical/continuous variable
• size - Point/line size encoding
• style - Marker/line style encoding
• col, row - Facet into multiple subplots (figure-level only)

# Scatter with multiple semantic mappings
sns.scatterplot(data=df, x='total_bill', y='tip',
                hue='time', size='size', style='sex')

# Line plot with confidence intervals
sns.lineplot(data=timeseries, x='date', y='value', hue='category')

# Faceted relational plot
sns.relplot(data=df, x='total_bill', y='tip',
            col='time', row='sex', hue='smoker', kind='scatter')

Distribution Plots (Single and Bivariate Distributions)

Use for: Understanding data spread, shape, and probability density

• histplot() - Bar-based frequency distributions with flexible binning
• kdeplot() - Smooth density estimates using Gaussian kernels
• ecdfplot() - Empirical cumulative distribution (no parameters to tune)
• rugplot() - Individual observation tick marks
• displot() - Figure-level interface for univariate and bivariate distributions
• jointplot() - Bivariate plot with marginal distributions
• pairplot() - Matrix of pairwise relationships across dataset

Key parameters:

• x, y - Variables (y optional for univariate)
• hue - Separate distributions by category
• stat - Normalization: "count", "frequency", "probability", "density"
• bins / binwidth - Histogram binning control
• bw_adjust - KDE bandwidth multiplier (higher = smoother)
• fill - Fill area under curve
• multiple - How to handle hue: "layer", "stack", "dodge", "fill"

# Histogram with density normalization
sns.histplot(data=df, x='total_bill', hue='time',
             stat='density', multiple='stack')

# Bivariate KDE with contours
sns.kdeplot(data=df, x='total_bill', y='tip',
            fill=True, levels=5, thresh=0.1)

# Joint plot with marginals
sns.jointplot(data=df, x='total_bill', y='tip',
              kind='scatter', hue='time')

# Pairwise relationships
sns.pairplot(data=df, hue='species', corner=True)

Categorical Plots (Comparisons Across Categories)

Use for: Comparing distributions or statistics across discrete categories

Categorical scatterplots:

• stripplot() - Points with jitter to show all observations
• swarmplot() - Non-overlapping points (beeswarm algorithm)

Distribution comparisons:

• boxplot() - Quartiles and outliers
• violinplot() - KDE + quartile information
• boxenplot() - Enhanced boxplot for larger datasets

Statistical estimates:

• barplot() - Mean/aggregate with confidence intervals
• pointplot() - Point estimates with connecting lines
• countplot() - Count of observations per category

Figure-level:

• catplot() - Faceted categorical plots (set kind parameter)

Key parameters:

• x, y - Variables (one typically categorical)
• hue - Additional categorical grouping
• order, hue_order - Control category ordering
• native_scale - Preserve numeric/datetime scale on the categorical axis
• log_scale - Apply log scaling without dropping down to matplotlib
• formatter - Control categorical tick labels
• dodge, gap - Separate hue levels side-by-side and space dodged elements
• orient - "x"/"y" or "v"/"h" to specify the categorical axis
• legend - True/False or "auto", "brie