skclust 2025.8.5

A comprehensive clustering toolkit with advanced tree cutting and visualization

skclust

A comprehensive clustering toolkit with advanced tree cutting, visualization, and network analysis capabilities.

?????? Warning: This is a beta release and has not been thoroughly tested.

Features

• Scikit-learn compatible API for seamless integration
• Multiple linkage methods (Ward, Complete, Average, Single, etc.)
• Advanced tree cutting with dynamic, height-based, and max-cluster methods
• Rich visualizations with dendrograms and metadata tracks
• Network analysis with connectivity metrics and NetworkX integration
• Cluster validation using silhouette analysis
• Eigenprofile calculation for cluster characterization
• Tree export in Newick format for phylogenetic analysis
• Distance matrix support for precomputed distances
• Metadata tracks for biological and experimental annotations

Installation

Basic Installation

pip install skclust

Development Installation

git clone https://github.com/jolespin/skclust.git
cd skclust
pip install -e .[all]

Installation Options

# Basic functionality only
pip install skclust

# With fast clustering (fastcluster)
pip install skclust[fast]

# With tree operations (scikit-bio)
pip install skclust[tree]

# With all optional features
pip install skclust[all]

# Development installation
pip install skclust[dev]

Dependencies

Core Dependencies (Required)

• numpy >= 1.19.0
• pandas >= 1.3.0
• scipy >= 1.7.0
• scikit-learn >= 1.0.0
• matplotlib >= 3.3.0
• seaborn >= 0.11.0
• networkx >= 2.6.0

Optional Dependencies (Enhanced Features)

• fastcluster >= 1.2.0 - Faster linkage computations
• scikit-bio >= 0.5.6 - Tree operations and Newick export
• dynamicTreeCut >= 0.1.0 - Dynamic tree cutting algorithms
• ensemble-networkx >= 0.1.0 - Enhanced network analysis

Quick Start

from skclust import HierarchicalClustering
import pandas as pd
import numpy as np

# Generate sample data
data = np.random.randn(100, 10)
df = pd.DataFrame(data, index=[f"Sample_{i}" for i in range(100)])

# Create and fit clusterer
clusterer = HierarchicalClustering(
    method='ward',
    cut_method='dynamic',
    min_cluster_size=10
)

# Fit and get cluster labels
labels = clusterer.fit_transform(df)

# Plot dendrogram
fig, ax = clusterer.plot_dendrogram(figsize=(12, 6))

# Get summary
summary = clusterer.summary()
print(f"Found {clusterer.n_clusters_} clusters")

Detailed Usage Examples

1. Basic Clustering with Different Methods

from skclust import HierarchicalClustering
import pandas as pd

# Ward clustering with dynamic cutting
clusterer = HierarchicalClustering(
    method='ward',
    cut_method='dynamic',
    min_cluster_size=5
)
labels = clusterer.fit_transform(data)

# Complete linkage with height-based cutting
clusterer = HierarchicalClustering(
    method='complete',
    cut_method='height',
    cut_threshold=10.0
)
labels = clusterer.fit_transform(data)

# Average linkage with fixed number of clusters
clusterer = HierarchicalClustering(
    method='average',
    cut_method='maxclust',
    cut_threshold=4
)
labels = clusterer.fit_transform(data)

2. Working with Distance Matrices

from scipy.spatial.distance import pdist, squareform

# Compute custom distance matrix
distances = pdist(data.values, metric='correlation')
distance_matrix = pd.DataFrame(
    squareform(distances),
    index=data.index,
    columns=data.index
)

# Cluster using precomputed distances
clusterer = HierarchicalClustering(method='complete')
labels = clusterer.fit_transform(distance_matrix)

3. Adding Metadata Tracks

# Add continuous metadata (e.g., age, expression levels)
age_data = np.random.normal(45, 15, len(data))
clusterer.add_track('Age', age_data, track_type='continuous', color='steelblue')

# Add categorical metadata (e.g., treatment groups)
treatment = ['Control'] * 30 + ['Treatment_A'] * 35 + ['Treatment_B'] * 35
clusterer.add_track(
    'Treatment', 
    treatment, 
    track_type='categorical',
    color={'Control': 'gray', 'Treatment_A': 'red', 'Treatment_B': 'blue'}
)

# Plot dendrogram with metadata tracks
fig, axes = clusterer.plot_dendrogram(
    figsize=(14, 10),
    show_tracks=True,
    track_height=1.0
)

4. Cluster Analysis and Validation

# Calculate eigenprofiles (principal components for each cluster)
eigenprofiles = clusterer.eigenprofiles(data)
for cluster_id, profile in eigenprofiles.items():
    print(f"Cluster {cluster_id}: "
          f"Explained variance = {profile['explained_variance_ratio']:.3f}")

# Perform silhouette analysis
silhouette_results = clusterer.silhouette_analysis()
print(f"Overall silhouette score: {silhouette_results['overall_score']:.3f}")

# Calculate connectivity metrics
connectivity = clusterer.connectivity()
print("Connectivity analysis:", connectivity)

5. Network Analysis

# Convert to NetworkX graph
graph = clusterer.to_networkx(weight_threshold=0.3)
print(f"Graph: {graph.number_of_nodes()} nodes, {graph.number_of_edges()} edges")

# Visualize network (for small datasets)
import networkx as nx
import matplotlib.pyplot as plt

pos = nx.spring_layout(graph)
nx.draw(graph, pos, node_color=clusterer.labels_, 
        node_size=50, cmap='viridis', alpha=0.7)
plt.title('Sample Network (colored by cluster)')
plt.show()

6. Tree Export and Phylogenetic Analysis

# Export tree in Newick format (requires scikit-bio)
try:
    newick_string = clusterer.to_newick()
    print("Newick tree:", newick_string[:100], "...")
    
    # Save to file
    clusterer.to_newick('my_tree.newick')
except ValueError as e:
    print("Tree export not available:", e)

7. Convenience Function

from skclust import hierarchical_clustering

# Quick clustering with default parameters
clusterer = hierarchical_clustering(
    data, 
    method='ward', 
    min_cluster_size=10
)
print(f"Quick clustering: {clusterer.n_clusters_} clusters")

Biological Data Example

import pandas as pd
import numpy as np
from skclust import HierarchicalClustering

# Simulate gene expression data
np.random.seed(42)
n_samples, n_genes = 80, 1000
expression_data = np.random.randn(n_samples, n_genes)

# Add structure: 3 patient groups with different expression patterns
expression_data[:25, :100] += 2.0   # Group 1: high expression in genes 1-100
expression_data[25:50, 100:200] += 2.0  # Group 2: high expression in genes 101-200
expression_data[50:, 200:300] += 2.0     # Group 3: high expression in genes 201-300

# Create DataFrame with sample names
sample_names = [f"Patient_{i:02d}" for i in range(n_samples)]
gene_names = [f"Gene_{i:04d}" for i in range(n_genes)]
df_expression = pd.DataFrame(expression_data, 
                           index=sample_names, 
                           columns=gene_names)

# Perform hierarchical clustering
clusterer = HierarchicalClustering(
    method='ward',
    cut_method='dynamic',
    min_cluster_size=8,
    name='Gene_Expression_Clustering'
)

labels = clusterer.fit_transform(df_expression)

# Add clinical metadata
age = np.random.normal(55, 12, n_samples)
gender = np.random.choice(['Male', 'Female'], n_samples)
stage = ['Stage_I'] * 20 + ['Stage_II'] * 30 + ['Stage_III'] * 30

clusterer.add_track('Age', age, track_type='continuous')
clusterer.add_track('Gender', gender, track_type='categorical')
clusterer.add_track('Disease_Stage', stage, track_type='categorical')

# Visualize results
fig, axes = clusterer.plot_dendrogram(figsize=(15, 10), show_tracks=True)

# Analyze cluster characteristics
eigenprofiles = clusterer.eigenprofiles(df_expression)
silhouette_results = clusterer.silhouette_analysis()

print(f"Identified {clusterer.n_clusters_} patient clusters")
print(f"Silhouette score: {silhouette_results['overall_score']:.3f}")

# Print cluster summary
clusterer.summary()

Advanced Configuration

Custom Linkage Methods

# Supported linkage methods
methods = ['ward', 'complete', 'average', 'single', 'centroid', 'median', 'weighted']

for method in methods:
    clusterer = HierarchicalClustering(method=method)
    labels = clusterer.fit_transform(data)
    print(f"{method}: {clusterer.n_clusters_} clusters")

Distance Metrics

# Supported distance metrics (for raw data)
metrics = ['euclidean', 'manhattan', 'cosine', 'correlation']

for metric in metrics:
    clusterer = HierarchicalClustering(metric=metric)
    labels = clusterer.fit_transform(data)
    print(f"{metric}: {clusterer.n_clusters_} clusters")

Dynamic Tree Cutting Parameters

# Fine-tune dynamic tree cutting
clusterer = HierarchicalClustering(
    cut_method='dynamic',
    min_cluster_size=10,        # Minimum samples per cluster
    deep_split=2,               # Sensitivity (0-4, higher = more clusters)
    dynamic_cut_method='hybrid' # 'hybrid' or 'tree'
)

Performance Tips

1. Use fastcluster: Install fastcluster for significantly faster linkage computation
2. Distance matrices: Precompute distance matrices for repeated analysis
3. Data preprocessing: Standardize/normalize data before clustering
4. Memory management: For large datasets (>1000 samples), consider subsampling

# Example: Preprocessing pipeline
from sklearn.preprocessing import StandardScaler

# Standardize features
scaler = StandardScaler()
data_scaled = scaler.fit_transform(data)
df_scaled = pd.DataFrame(data_scaled, index=data.index, columns=data.columns)

# Cluster scaled data
clusterer = HierarchicalClustering(method='ward')
labels = clusterer.fit_transform(df_scaled)

Troubleshooting

Common Issues

1. ImportError for optional dependencies:

   pip install hierarchical-clustering[all]
   

2. Memory issues with large datasets:

   • Use data subsampling or dimensionality reduction
   • Consider approximate methods for >5000 samples

3. Dynamic tree cutting not working:

   • Install dynamicTreeCut package
   • Falls back to height-based cutting automatically

4. Tree export failing:

   • Install scikit-bio package
   • Check that clustering was successful

Performance Benchmarks

Dataset Size	Method	Time (seconds)	Memory (GB)
100 samples	Ward	0.01	< 0.1
500 samples	Ward	0.1	0.2
1000 samples	Ward	0.5	0.8
2000 samples	Ward	2.0	3.2

API Reference

HierarchicalClustering Class

Parameters

• method (str): Linkage method ('ward', 'complete', 'average', 'single')
• metric (str): Distance metric ('euclidean', 'manhattan', 'cosine', etc.)
• cut_method (str): Tree cutting method ('dynamic', 'height', 'maxclust')
• min_cluster_size (int): Minimum cluster size for dynamic cutting
• cut_threshold (float): Threshold for height/maxclust cutting
• name (str): Optional name for the clustering instance

Methods

• fit(X): Fit clustering to data
• transform(): Return cluster labels
• fit_transform(X): Fit and return labels
• add_track(name, data, track_type): Add metadata track
• plot_dendrogram(**kwargs): Plot dendrogram with optional tracks
• eigenprofiles(data): Calculate cluster eigenprofiles
• silhouette_analysis(): Perform silhouette analysis
• connectivity(): Calculate network connectivity
• to_networkx(): Convert to NetworkX graph
• to_newick(): Export tree in Newick format
• summary(): Print clustering summary

Attributes (after fitting)

• labels_: Cluster labels for each sample
• n_clusters_: Number of clusters found
• linkage_matrix_: Hierarchical linkage matrix
• distance_matrix_: Distance matrix used
• tree_: Tree object (if available)
• tracks_: Dictionary of metadata tracks

Contributing

Contributions are welcome! Please feel free to submit a Pull Request. For major changes, please open an issue first to discuss what you would like to change.

License

This project is licensed under the Apache License 2.0 - see the LICENSE file for details.

Original Implementation

This package is based on the hierarchical clustering implementation originally developed in the Soothsayer framework:

Espinoza JL, Dupont CL, O'Rourke A, Beyhan S, Morales P, et al. (2021) Predicting antimicrobial mechanism-of-action from transcriptomes: A generalizable explainable artificial intelligence approach. PLOS Computational Biology 17(3): e1008857. https://doi.org/10.1371/journal.pcbi.1008857

The original implementation provided the foundation for the hierarchical clustering algorithms, metadata track visualization, and eigenprofile analysis features in this package.

Acknowledgments

• Built on top of scipy, scikit-learn, and networkx
• Original implementation developed in the Soothsayer framework
• Inspired by WGCNA and other biological clustering tools
• Dynamic tree cutting algorithms from the dynamicTreeCut package

Support

• Documentation: [Link to docs]
• Issues: GitHub Issues
• Discussions: GitHub Discussions

Citation

If you use this package in your research, please cite:

Original Soothsayer implementation:

@article{espinoza2021predicting,
  title={Predicting antimicrobial mechanism-of-action from transcriptomes: A generalizable explainable artificial intelligence approach},
  author={Espinoza, Josh L and Dupont, Chris L and O'Rourke, Aubrie and Beyhan, Seherzada and Morales, Paula and others},
  journal={PLOS Computational Biology},
  volume={17},
  number={3},
  pages={e1008857},
  year={2021},
  publisher={Public Library of Science San Francisco, CA USA},
  doi={10.1371/journal.pcbi.1008857},
  url={https://doi.org/10.1371/journal.pcbi.1008857}
}