# Exploratory Data Analysis
Overview
Perform comprehensive exploratory data analysis (EDA) on scientific data files across multiple domains. This skill provides automated file type detection, format-specific analysis, data quality assessment, and generates detailed markdown reports suitable for documentation and downstream analysis planning.
**Key Capabilities:** - Automatic detection and analysis of 200+ scientific file formats - Comprehensive format-specific metadata extraction - Data quality and integrity assessment - Statistical summaries and distributions - Visualization recommendations - Downstream analysis suggestions - Markdown report generation
When to Use This Skill
Use this skill when: - User provides a path to a scientific data file for analysis - User asks to "explore", "analyze", or "summarize" a data file - User wants to understand the structure and content of scientific data - User needs a comprehensive report of a dataset before analysis - User wants to assess data quality or completeness - User asks what type of analysis is appropriate for a file
Supported File Categories
The skill has comprehensive coverage of scientific file formats organized into six major categories:
### 1. Chemistry and Molecular Formats (60+ extensions) Structure files, computational chemistry outputs, molecular dynamics trajectories, and chemical databases.
**File types include:** `.pdb`, `.cif`, `.mol`, `.mol2`, `.sdf`, `.xyz`, `.smi`, `.gro`, `.log`, `.fchk`, `.cube`, `.dcd`, `.xtc`, `.trr`, `.prmtop`, `.psf`, and more.
**Reference file:** `references/chemistry_molecular_formats.md`
### 2. Bioinformatics and Genomics Formats (50+ extensions) Sequence data, alignments, annotations, variants, and expression data.
**File types include:** `.fasta`, `.fastq`, `.sam`, `.bam`, `.vcf`, `.bed`, `.gff`, `.gtf`, `.bigwig`, `.h5ad`, `.loom`, `.counts`, `.mtx`, and more.
**Reference file:** `references/bioinformatics_genomics_formats.md`
### 3. Microscopy and Imaging Formats (45+ extensions) Microscopy images, medical imaging, whole slide imaging, and electron microscopy.
**File types include:** `.tif`, `.nd2`, `.lif`, `.czi`, `.ims`, `.dcm`, `.nii`, `.mrc`, `.dm3`, `.vsi`, `.svs`, `.ome.tiff`, and more.
**Reference file:** `references/microscopy_imaging_formats.md`
### 4. Spectroscopy and Analytical Chemistry Formats (35+ extensions) NMR, mass spectrometry, IR/Raman, UV-Vis, X-ray, chromatography, and other analytical techniques.
**File types include:** `.fid`, `.mzML`, `.mzXML`, `.raw`, `.mgf`, `.spc`, `.jdx`, `.xy`, `.cif` (crystallography), `.wdf`, and more.
**Reference file:** `references/spectroscopy_analytical_formats.md`
### 5. Proteomics and Metabolomics Formats (30+ extensions) Mass spec proteomics, metabolomics, lipidomics, and multi-omics data.
**File types include:** `.mzML`, `.pepXML`, `.protXML`, `.mzid`, `.mzTab`, `.sky`, `.mgf`, `.msp`, `.h5ad`, and more.
**Reference file:** `references/proteomics_metabolomics_formats.md`
### 6. General Scientific Data Formats (30+ extensions) Arrays, tables, hierarchical data, compressed archives, and common scientific formats.
**File types include:** `.npy`, `.npz`, `.csv`, `.xlsx`, `.json`, `.hdf5`, `.zarr`, `.parquet`, `.mat`, `.fits`, `.nc`, `.xml`, and more.
**Reference file:** `references/general_scientific_formats.md`
Workflow
Step 1: File Type Detection
When a user provides a file path, first identify the file type:
- Extract the file extension
- Look up the extension in the appropriate reference file
- Identify the file category and format description
- Load format-specific information
**Example:** ``` User: "Analyze data.fastq" → Extension: .fastq → Category: bioinformatics_genomics → Format: FASTQ Format (sequence data with quality scores) → Reference: references/bioinformatics_genomics_formats.md ```
Step 2: Load Format-Specific Information
Based on the file type, read the corresponding reference file to understand: - **Typical Data:** What kind of data this format contains - **Use Cases:** Common applications for this format - **Python Libraries:** How to read the file in Python - **EDA Approach:** What analyses are appropriate for this data type
Search the reference file for the specific extension (e.g., search for "### .fastq" in `bioinformatics_genomics_formats.md`).
Step 3: Perform Data Analysis
Use the `scripts/eda_analyzer.py` script OR implement custom analysis:
**Option A: Use the analyzer script** ```python # The script automatically: # 1. Detects file type # 2. Loads reference information # 3. Performs format-specific analysis # 4. Generates markdown report
python scripts/eda_analyzer.py <filepath> [output.md] ```
**Option B: Custom analysis in the conversation** Based on the format information from the reference file, perform appropriate analysis:
For tabular data (CSV, TSV, Excel): - Load with pandas - Check dimensions, data types - Analyze missing values - Calculate summary statistics - Identify outliers - Check for duplicates
For sequence data (FASTA, FASTQ): - Count sequences - Analyze length distributions - Calculate GC content - Assess quality scores (FASTQ)
For images (TIFF, ND2, CZI): - Check dimensions (X, Y, Z, C, T) - Analyze bit depth and value range - Extract metadata (channels, timestamps, spatial calibration) - Calculate intensity statistics
For arrays (NPY, HDF5): - Check shape and dimensions - Analyze data type - Calculate statistical summaries - Check for missing/invalid values
Step 4: Generate Comprehensive Report
Create a markdown report with the following sections:
#### Required Sections: 1. **Title and Metadata** - Filename and timestamp - File size and location
2. **Basic Information** - File properties - Format identification
3. **File Type Details** - Format description from reference - Typical data content - Common use cases - Python libraries for reading
4. **Data Analysis** - Structure and dimensions - Statistical summaries - Quality assessment - Data characteristics
5. **Key Findings** - Notable patterns - Potential issues - Quality metrics
6. **Recommendations** - Preprocessing steps - Appropriate analyses - Tools and methods - Visualization approaches
#### Template Location Use `assets/report_template.md` as a guide for report structure.
Step 5: Save Report
Save the markdown report with a descriptive filename: - Pattern: `{original_filename}_eda_report.md` - Example: `experiment_data.fastq` → `experiment_data_eda_report.md`
Detailed Format References
Each reference file contains comprehensive information for dozens of file types. To find information about a specific format:
- Identify the category from the extension
- Read the appropriate reference file
- Search for the section heading matching the extension (e.g., "### .pdb")
- Extract the format information
Reference File Structure
Each format entry includes: - **Description:** What the format is - **Typical Data:** What it contains - **Use Cases:** Common applications - **Python Libraries:** How to read it (with code examples) - **EDA Approach:** Specific analyses to perform
**Example lookup:** ```markdown ### .pdb - Protein Data Bank **Description:** Standard format for 3D structures of biological macromolecules **Typical Data:** Atomic coordinates, residue information, secondary structure **Use Cases:** Protein structure analysis, molecular visualization, docking **Python Libraries:** - `Biopython`: `Bio.PDB` - `MDAnalysis`: `MDAnalysis.Universe('file.pdb')` **EDA Approach:** - Structure validation (bond lengths, angles) - B-factor distribution - Missing residues detection - Ramachandran plots ```
Best Practices
Reading Reference Files
Reference files are large (10,000+ words each). To efficiently use them:
1. **Search by extension:** Use grep to find the specific format ```python import re with open('references/chemistry_molecular_formats.md', 'r') as f: content = f.read() pattern = r'### \.pdb[^#]*?(?=###|\Z)' match = re.search(pattern, content, re.IGNORECASE | re.DOTALL) ```
- **Extract relevant sections:** Don't load entire reference files into context unnecessarily
- **Cache format info:** If analyzing multiple files of the same type, reuse the format information
Data Analysis
- **Sample large files:** For files with millions of records, analyze a representative sample
- **Handle errors gracefully:** Many scientific formats require specific libraries; provide clear installation instructions
- **Validate metadata:** Cross-check metadata consistency (e.g., stated dimensions vs actual data)
- **Consider data provenance:** Note instrument, software versions, processing steps
Report Generation
- **Be comprehensive:** Include all relevant information for downstream analysis
- **Be specific:** Provide concrete recommendations based on the file type
- **Be actionable:** Suggest specific next steps and tools
- **Include code examples:** Show how to load and work with the data
Examples
Example 1: Analyzing a FASTQ file
```python # User provides: "Analyze reads.fastq"
# 1. Detect file type extension = '.fastq' category = 'bioinformatics_genomics'
# 2. Read reference info # Search references/bioinformatics_genomics_formats.md for "### .fastq"
# 3. Perform analysis from Bio import SeqIO sequences = list(SeqIO.parse('reads.fastq', 'fastq')) # Calculate: read count, length distribution, quality scores, GC content
# 4. Generate report # Include: format description, analysis results, QC recommendations
# 5. Save as: reads_eda_report.md ```
Example 2: Analyzing a CSV dataset
```python # User provides: "Explore experiment_results.csv"
1. Detect: .csv → general_scientific
2. Load reference for CSV format
# 3. Analyze import pandas as pd df = pd.read_csv('experiment_results.csv') # Dimensions, dtypes, missing values, statistics, correlations
# 4. Generate report with: # - Data structure # - Missing value patterns # - Statistical summaries # - Correlation matrix # - Outlier detection results
# 5. Save report ```
Example 3: Analyzing microscopy data
```python # User provides: "Analyze cells.nd2"
1. Detect: .nd2 → microscopy_imaging (Nikon format)
# 2. Read reference for ND2 format # Learn: multi-dimensional (XYZCT), requires nd2reader
# 3. Analyze from nd2reader import ND2Reader with ND2Reader('cells.nd2') as images: # Extract: dimensions, channels, timepoints, metadata # Calculate: intensity statistics, frame info
# 4. Generate report with: # - Image dimensions (XY, Z-stacks, time, channels) # - Channel wavelengths # - Pixel size and calibration # - Recommendations for image analysis
# 5. Save report ```
Troubleshooting
Missing Libraries
Many scientific formats require specialized libraries:
**Problem:** Import error when trying to read a file
**Solution:** Provide clear installation instructions ```python try: from Bio import SeqIO except ImportError: print("Install Biopython: uv pip install biopython") ```
Common requirements by category: - **Bioinformatics:** `biopython`, `pysam`, `pyBigWig` - **Chemistry:** `rdkit`, `mdanalysis`, `cclib` - **Microscopy:** `tifffile`, `nd2reader`, `aicsimageio`, `pydicom` - **Spectroscopy:** `nmrglue`, `pymzml`, `pyteomics` - **General:** `pandas`, `numpy`, `h5py`, `scipy`
Unknown File Types
If a file extension is not in the references:
- Ask the user about the file format
- Check if it's a vendor-specific variant
- Attempt generic analysis based on file structure (text vs binary)
- Provide general recommendations
Large Files
For very large files:
- Use sampling strategies (first N records)
- Use memory-mapped access (for HDF5, NPY)
- Process in chunks (for CSV, FASTQ)
- Provide estimates based on samples
Script Usage
The `scripts/eda_analyzer.py` can be used directly:
```bash # Basic usage python scripts/eda_analyzer.py data.csv
# Specify output file python scripts/eda_analyzer.py data.csv output_report.md
# The script will: # 1. Auto-detect file type # 2. Load format references # 3. Perform appropriate analysis # 4. Generate markdown report ```
The script supports automatic analysis for many common formats, but custom analysis in the conversation provides more flexibility and domain-specific insights.
Advanced Usage
Multi-File Analysis
When analyzing multiple related files: 1. Perform individual EDA on each file 2. Create a summary comparison report 3. Identify relationships and dependencies 4. Suggest integration strategies
Quality Control
For data quality assessment: 1. Check format compliance 2. Validate metadata consistency 3. Assess completeness 4. Identify outliers and anomalies 5. Compare to expected ranges/distributions
Preprocessing Recommendations
Based on data characteristics, recommend: 1. Normalization strategies 2. Missing value imputation 3. Outlier handling 4. Batch correction 5. Format conversions
Resources
### scripts/ - `eda_analyzer.py`: Comprehensive analysis script that can be run directly or imported
### references/ - `chemistry_molecular_formats.md`: 60+ chemistry/molecular file formats - `bioinformatics_genomics_formats.md`: 50+ bioinformatics formats - `microscopy_imaging_formats.md`: 45+ imaging formats - `spectroscopy_analytical_formats.md`: 35+ spectroscopy formats - `proteomics_metabolomics_formats.md`: 30+ omics formats - `general_scientific_formats.md`: 30+ general formats
### assets/ - `report_template.md`: Comprehensive markdown template for EDA reports