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---
name: arboreto
description: "Gene regulatory network inference with GRNBoost2/GENIE3 algorithms. Infer TF-target relationships from expression data, scalable with Dask, for scRNA-seq and GRN analysis."
description: Infer gene regulatory networks (GRNs) from gene expression data using scalable algorithms (GRNBoost2, GENIE3). Use when analyzing transcriptomics data (bulk RNA-seq, single-cell RNA-seq) to identify transcription factor-target gene relationships and regulatory interactions. Supports distributed computation for large-scale datasets.
---
# Arboreto - Gene Regulatory Network Inference
# Arboreto
## Overview
Arboreto is a Python library for inferring gene regulatory networks (GRNs) from gene expression data using machine learning algorithms. It enables scalable GRN inference from single machines to multi-node clusters using Dask for distributed computing. The skill provides comprehensive support for both GRNBoost2 (fast gradient boosting) and GENIE3 (Random Forest) algorithms.
Arboreto is a computational library for inferring gene regulatory networks (GRNs) from gene expression data using parallelized algorithms that scale from single machines to multi-node clusters.
## When to Use This Skill
**Core capability**: Identify which transcription factors (TFs) regulate which target genes based on expression patterns across observations (cells, samples, conditions).
This skill should be used when:
- Inferring regulatory relationships between genes from expression data
- Analyzing single-cell or bulk RNA-seq data to identify transcription factor targets
- Building the GRN inference component of a pySCENIC pipeline
- Comparing GRNBoost2 and GENIE3 algorithm performance
- Setting up distributed computing for large-scale genomic analyses
- Troubleshooting arboreto installation or runtime issues
## Quick Start
Install arboreto:
```bash
pip install arboreto
```
Basic GRN inference:
```python
import pandas as pd
from arboreto.algo import grnboost2
if __name__ == '__main__':
# Load expression data (genes as columns)
expression_matrix = pd.read_csv('expression_data.tsv', sep='\t')
# Infer regulatory network
network = grnboost2(expression_data=expression_matrix)
# Save results (TF, target, importance)
network.to_csv('network.tsv', sep='\t', index=False, header=False)
```
**Critical**: Always use `if __name__ == '__main__':` guard because Dask spawns new processes.
## Core Capabilities
### 1. Basic GRN Inference
For standard gene regulatory network inference tasks:
For standard GRN inference workflows including:
- Input data preparation (Pandas DataFrame or NumPy array)
- Running inference with GRNBoost2 or GENIE3
- Filtering by transcription factors
- Output format and interpretation
**Key considerations:**
- Expression data format: Rows = observations (cells/samples), Columns = genes
- If data has genes as rows, transpose it first: `expression_df.T`
- Always include `seed` parameter for reproducible results
- Transcription factor list is optional but recommended for focused analysis
**See**: `references/basic_inference.md`
**Typical workflow:**
```python
import pandas as pd
from arboreto.algo import grnboost2
from arboreto.utils import load_tf_names
# Load expression data (ensure correct orientation)
expression_data = pd.read_csv('expression_data.tsv', sep='\t', index_col=0)
# Optional: Load TF names
tf_names = load_tf_names('transcription_factors.txt')
# Run inference
network = grnboost2(
expression_data=expression_data,
tf_names=tf_names,
seed=42 # For reproducibility
)
# Save results
network.to_csv('network_output.tsv', sep='\t', index=False)
```
**Output format:**
- DataFrame with columns: `['TF', 'target', 'importance']`
- Higher importance scores indicate stronger predicted regulatory relationships
- Typically sorted by importance (descending)
**Multiprocessing requirement:**
All arboreto code must include `if __name__ == '__main__':` protection due to Dask's multiprocessing requirements:
```python
if __name__ == '__main__':
# Arboreto code goes here
network = grnboost2(expression_data=expr_data, seed=42)
**Use the ready-to-run script**: `scripts/basic_grn_inference.py` for standard inference tasks:
```bash
python scripts/basic_grn_inference.py expression_data.tsv output_network.tsv --tf-file tfs.txt --seed 777
```
### 2. Algorithm Selection
**GRNBoost2 (Recommended for most cases):**
- ~10-100x faster than GENIE3
- Uses stochastic gradient boosting with early-stopping
- Best for: Large datasets (>10k observations), time-sensitive analyses
- Function: `arboreto.algo.grnboost2()`
Arboreto provides two algorithms:
**GENIE3:**
- Uses Random Forest regression
- More established, classical approach
- Best for: Small datasets, methodological comparisons, reproducing published results
- Function: `arboreto.algo.genie3()`
**GRNBoost2 (Recommended)**:
- Fast gradient boosting-based inference
- Optimized for large datasets (10k+ observations)
- Default choice for most analyses
**When to compare both algorithms:**
Use the provided `compare_algorithms.py` script when:
- Validating results for critical analyses
- Benchmarking performance on new datasets
- Publishing research requiring methodological comparisons
**GENIE3**:
- Random Forest-based inference
- Original multiple regression approach
- Use for comparison or validation
Quick comparison:
```python
from arboreto.algo import grnboost2, genie3
# Fast, recommended
network_grnboost = grnboost2(expression_data=matrix)
# Classic algorithm
network_genie3 = genie3(expression_data=matrix)
```
**For detailed algorithm comparison, parameters, and selection guidance**: `references/algorithms.md`
### 3. Distributed Computing
**Local execution (default):**
Arboreto automatically creates a local Dask client. No configuration needed:
Scale inference from local multi-core to cluster environments:
**Local (default)** - Uses all available cores automatically:
```python
network = grnboost2(expression_data=expr_data)
network = grnboost2(expression_data=matrix)
```
**Custom local cluster (recommended for better control):**
**Custom local client** - Control resources:
```python
from dask.distributed import Client, LocalCluster
from distributed import LocalCluster, Client
# Configure cluster
cluster = LocalCluster(
n_workers=4,
threads_per_worker=2,
memory_limit='4GB',
diagnostics_port=8787 # Dashboard at http://localhost:8787
)
client = Client(cluster)
local_cluster = LocalCluster(n_workers=10, memory_limit='8GB')
client = Client(local_cluster)
# Run inference
network = grnboost2(
expression_data=expr_data,
client_or_address=client
)
network = grnboost2(expression_data=matrix, client_or_address=client)
# Clean up
client.close()
cluster.close()
local_cluster.close()
```
**Distributed cluster (multi-node):**
On scheduler node:
```bash
dask-scheduler --no-bokeh
```
On worker nodes:
```bash
dask-worker scheduler-address:8786 --local-dir /tmp
```
In Python:
**Cluster computing** - Connect to remote Dask scheduler:
```python
from dask.distributed import Client
from distributed import Client
client = Client('scheduler-address:8786')
network = grnboost2(expression_data=expr_data, client_or_address=client)
client = Client('tcp://scheduler:8786')
network = grnboost2(expression_data=matrix, client_or_address=client)
```
### 4. Data Preparation
**Common data format issues:**
1. **Transposed data** (genes as rows instead of columns):
```python
# If genes are rows, transpose
expression_data = pd.read_csv('data.tsv', sep='\t', index_col=0).T
```
2. **Missing gene names:**
```python
# Provide gene names if using numpy array
network = grnboost2(
expression_data=expr_array,
gene_names=['Gene1', 'Gene2', 'Gene3', ...],
seed=42
)
```
3. **Transcription factor specification:**
```python
# Option 1: Python list
tf_names = ['Sox2', 'Oct4', 'Nanog', 'Klf4']
# Option 2: Load from file (one TF per line)
from arboreto.utils import load_tf_names
tf_names = load_tf_names('tf_names.txt')
```
### 5. Reproducibility
Always specify a seed for consistent results:
```python
network = grnboost2(expression_data=expr_data, seed=42)
```
Without a seed, results will vary between runs due to algorithm randomness.
### 6. Result Interpretation
**Understanding the output:**
- `TF`: Transcription factor (regulator) gene
- `target`: Target gene being regulated
- `importance`: Strength of predicted regulatory relationship
**Typical post-processing:**
```python
# Filter by importance threshold
high_confidence = network[network['importance'] > 10]
# Get top N predictions
top_predictions = network.head(1000)
# Find all targets of a specific TF
sox2_targets = network[network['TF'] == 'Sox2']
# Count regulations per TF
tf_counts = network['TF'].value_counts()
```
**For cluster setup, performance optimization, and large-scale workflows**: `references/distributed_computing.md`
## Installation
**Recommended (via conda):**
**Recommended (Conda)**:
```bash
conda install -c bioconda arboreto
```
**Via pip:**
**Alternative (pip)**:
```bash
pip install arboreto
```
**From source:**
```bash
git clone https://github.com/tmoerman/arboreto.git
cd arboreto
pip install .
```
**Dependencies:**
- pandas
- numpy
- scikit-learn
- scipy
- dask
- distributed
## Troubleshooting
### Issue: Bokeh error when launching Dask scheduler
**Error:** `TypeError: got an unexpected keyword argument 'host'`
**Solutions:**
- Use `dask-scheduler --no-bokeh` to disable Bokeh
- Upgrade to Dask distributed >= 0.20.0
### Issue: Workers not connecting to scheduler
**Symptoms:** Worker processes start but fail to establish connections
**Solutions:**
- Remove `dask-worker-space` directory before restarting workers
- Specify adequate `local_dir` when creating cluster:
```python
cluster = LocalCluster(
worker_kwargs={'local_dir': '/tmp'}
)
```
### Issue: Memory errors with large datasets
**Solutions:**
- Increase worker memory limits: `memory_limit='8GB'`
- Distribute across more nodes
- Reduce dataset size through preprocessing (e.g., feature selection)
- Ensure expression matrix fits in available RAM
### Issue: Inconsistent results across runs
**Solution:** Always specify a `seed` parameter:
```python
network = grnboost2(expression_data=expr_data, seed=42)
```
### Issue: Import errors or missing dependencies
**Solution:** Use conda installation to handle numerical library dependencies:
**For isolated environment**:
```bash
conda create --name arboreto-env
conda activate arboreto-env
conda install -c bioconda arboreto
```
## Provided Scripts
**Dependencies**: scipy, scikit-learn, numpy, pandas, dask, distributed
This skill includes ready-to-use scripts for common workflows:
## Common Use Cases
### scripts/basic_grn_inference.py
### Single-Cell RNA-seq Analysis
```python
import pandas as pd
from arboreto.algo import grnboost2
Command-line tool for standard GRN inference workflow.
if __name__ == '__main__':
# Load single-cell expression matrix (cells x genes)
sc_data = pd.read_csv('scrna_counts.tsv', sep='\t')
**Usage:**
```bash
python scripts/basic_grn_inference.py expression_data.tsv \
-t tf_names.txt \
-o network.tsv \
-s 42 \
--transpose # if genes are rows
# Infer cell-type-specific regulatory network
network = grnboost2(expression_data=sc_data, seed=42)
# Filter high-confidence links
high_confidence = network[network['importance'] > 0.5]
high_confidence.to_csv('grn_high_confidence.tsv', sep='\t', index=False)
```
**Features:**
- Automatic data loading and validation
- Optional TF list specification
- Configurable output format
- Data transposition support
- Summary statistics
### Bulk RNA-seq with TF Filtering
```python
from arboreto.utils import load_tf_names
from arboreto.algo import grnboost2
### scripts/distributed_inference.py
if __name__ == '__main__':
# Load data
expression_data = pd.read_csv('rnaseq_tpm.tsv', sep='\t')
tf_names = load_tf_names('human_tfs.txt')
GRN inference with custom Dask cluster configuration.
# Infer with TF restriction
network = grnboost2(
expression_data=expression_data,
tf_names=tf_names,
seed=123
)
**Usage:**
```bash
python scripts/distributed_inference.py expression_data.tsv \
-t tf_names.txt \
-w 8 \
-m 4GB \
--threads 2 \
--dashboard-port 8787
network.to_csv('tf_target_network.tsv', sep='\t', index=False)
```
**Features:**
- Configurable worker count and memory limits
- Dask dashboard integration
- Thread configuration
- Resource monitoring
### Comparative Analysis (Multiple Conditions)
```python
from arboreto.algo import grnboost2
### scripts/compare_algorithms.py
if __name__ == '__main__':
# Infer networks for different conditions
conditions = ['control', 'treatment_24h', 'treatment_48h']
Compare GRNBoost2 and GENIE3 side-by-side.
**Usage:**
```bash
python scripts/compare_algorithms.py expression_data.tsv \
-t tf_names.txt \
--top-n 100
for condition in conditions:
data = pd.read_csv(f'{condition}_expression.tsv', sep='\t')
network = grnboost2(expression_data=data, seed=42)
network.to_csv(f'{condition}_network.tsv', sep='\t', index=False)
```
**Features:**
- Runtime comparison
- Network statistics
- Prediction overlap analysis
- Top prediction comparison
## Output Interpretation
## Reference Documentation
Arboreto returns a DataFrame with regulatory links:
Detailed API documentation is available in [references/api_reference.md](references/api_reference.md), including:
- Complete parameter descriptions for all functions
- Data format specifications
- Distributed computing configuration
- Performance optimization tips
- Integration with pySCENIC
- Comprehensive examples
| Column | Description |
|--------|-------------|
| `TF` | Transcription factor (regulator) |
| `target` | Target gene |
| `importance` | Regulatory importance score (higher = stronger) |
Load this reference when:
- Working with advanced Dask configurations
- Troubleshooting complex deployment scenarios
- Understanding algorithm internals
- Optimizing performance for specific use cases
**Filtering strategy**:
- Top N links per target gene
- Importance threshold (e.g., > 0.5)
- Statistical significance testing (permutation tests)
## Integration with pySCENIC
Arboreto is the first step in the pySCENIC single-cell analysis pipeline:
Arboreto is a core component of the SCENIC pipeline for single-cell regulatory network analysis:
1. **GRN Inference (arboreto)** ← This skill
- Input: Expression matrix
- Output: Regulatory network
2. **Regulon Prediction (pySCENIC)**
- Input: Network from arboreto
- Output: Refined regulons
3. **Cell Type Identification (pySCENIC)**
- Input: Regulons
- Output: Cell type scores
When working with pySCENIC, use arboreto to generate the initial network, then pass results to the pySCENIC pipeline.
## Best Practices
1. **Always use seed parameter** for reproducible research
2. **Validate data orientation** (rows = observations, columns = genes)
3. **Specify TF list** when known to focus inference and improve speed
4. **Monitor with Dask dashboard** for distributed computing
5. **Save intermediate results** to avoid re-running long computations
6. **Filter results** by importance threshold for downstream analysis
7. **Use GRNBoost2 by default** unless specifically requiring GENIE3
8. **Include multiprocessing guard** (`if __name__ == '__main__':`) in all scripts
## Quick Reference
**Basic inference:**
```python
# Step 1: Use arboreto for GRN inference
from arboreto.algo import grnboost2
network = grnboost2(expression_data=expr_df, seed=42)
network = grnboost2(expression_data=sc_data, tf_names=tf_list)
# Step 2: Use pySCENIC for regulon identification and activity scoring
# (See pySCENIC documentation for downstream analysis)
```
**With TF specification:**
## Reproducibility
Always set a seed for reproducible results:
```python
network = grnboost2(expression_data=expr_df, tf_names=tf_list, seed=42)
network = grnboost2(expression_data=matrix, seed=777)
```
**With custom Dask client:**
Run multiple seeds for robustness analysis:
```python
from dask.distributed import Client, LocalCluster
cluster = LocalCluster(n_workers=4)
client = Client(cluster)
network = grnboost2(expression_data=expr_df, client_or_address=client, seed=42)
client.close()
cluster.close()
from distributed import LocalCluster, Client
if __name__ == '__main__':
client = Client(LocalCluster())
seeds = [42, 123, 777]
networks = []
for seed in seeds:
net = grnboost2(expression_data=matrix, client_or_address=client, seed=seed)
networks.append(net)
# Combine networks and filter consensus links
consensus = analyze_consensus(networks)
```
**Load TF names:**
```python
from arboreto.utils import load_tf_names
tf_names = load_tf_names('transcription_factors.txt')
```
## Troubleshooting
**Transpose data:**
```python
expression_df = pd.read_csv('data.tsv', sep='\t', index_col=0).T
```
**Memory errors**: Reduce dataset size by filtering low-variance genes or use distributed computing
**Slow performance**: Use GRNBoost2 instead of GENIE3, enable distributed client, filter TF list
**Dask errors**: Ensure `if __name__ == '__main__':` guard is present in scripts
**Empty results**: Check data format (genes as columns), verify TF names match gene names