HashPrep

Dataset Profiler & Debugger for Machine Learning

Overview

HashPrep is a Python library for intelligent dataset profiling and debugging that acts as a comprehensive pre-training quality assurance tool for machine learning projects. Think of it as "Pandas Profiling + PyLint for datasets", designed specifically for machine learning workflows.

It catches critical dataset issues before they derail your ML pipeline, explains the problems, and suggests context-aware fixes.
If you want, HashPrep can even apply those fixes for you automatically.

Features

Key features include:

• Intelligent Profiling: Detect missing values, skewed distributions, outliers, and data type inconsistencies.
• ML-Specific Checks: Identify data leakage, dataset drift, class imbalance, and high-cardinality features.
• Automated Preparation: Get suggestions for encoding, imputation, scaling, and transformations.
• Rich Reporting: Generate statistical summaries and exportable reports (HTML/PDF/Markdown/JSON) with embedded visualizations.
• Production-Ready Pipelines: Output reproducible cleaning and preprocessing code (fixes.py) that integrates seamlessly with ML workflows.
• Modern Themes: Choose between "Minimal" (professional) and "Neubrutalism" (bold) report styles.

Installation

Using pip

pip install hashprep

Using uv (recommended)

# Install uv if you haven't already
curl -LsSf https://astral.sh/uv/install.sh | sh

# Install hashprep
uv pip install hashprep

# Or for development from source
git clone https://github.com/cachevector/hashprep.git
cd hashprep
uv sync

After installation, the hashprep command will be available directly in your terminal.

Usage

HashPrep can be used both as a command-line tool and as a Python library.

CLI Usage

1. Quick Scan

Get a quick summary of critical issues in your terminal.

hashprep scan dataset.csv

Options:

• --critical-only: Show only critical issues
• --quiet: Minimal output (counts only)
• --json: Output in JSON format
• --target COLUMN: Specify target column for ML-specific checks
• --checks CHECKS: Run specific checks (comma-separated)
• --comparison FILE: Compare with another dataset for drift detection
• --sample-size N: Limit analysis to N rows
• --no-sample: Disable automatic sampling
• --config FILE: Load thresholds from a YAML/TOML/JSON config file

Example:

# Scan with target column and specific checks
hashprep scan train.csv --target Survived --checks outliers,high_missing_values,class_imbalance

# Quick scan with JSON output
hashprep scan dataset.csv --json --quiet

2. Detailed Analysis

Get comprehensive details about all detected issues.

hashprep details dataset.csv

Options: Same as scan command (including --config)

Example:

hashprep details train.csv --target Survived

3. Generate Reports

Generate comprehensive reports in multiple formats with visualizations.

hashprep report dataset.csv --format html --theme minimal

Options:

• --output PATH, -o PATH: Custom output file path
• --format {md,json,html,pdf}: Report format (default: md)
• --theme {minimal,neubrutalism}: HTML report theme (default: minimal)
• --with-code: Generate Python scripts for fixes and pipelines
• --full / --no-full: Include/exclude full summaries (default: True)
• --visualizations / --no-visualizations: Include/exclude plots (default: True)
• --target COLUMN: Specify target column
• --checks CHECKS: Run specific checks
• --comparison FILE: Compare with another dataset for drift detection
• --sample-size N: Limit analysis to N rows
• --no-sample: Disable automatic sampling
• --config FILE: Load thresholds from a YAML/TOML/JSON config file

Examples:

# Generate HTML report with minimal theme
hashprep report dataset.csv --format html --theme minimal --full

# Generate PDF report without visualizations (faster)
hashprep report dataset.csv --format pdf --no-visualizations

# Generate report with automatic fix scripts
hashprep report dataset.csv --with-code

# Generate report with custom output path
hashprep report dataset.csv --format html --output my_reports/analysis.html

# This creates:
# - dataset_hashprep_report.md (or .html/.pdf/.json)
# - dataset_hashprep_report_fixes.py (pandas script)
# - dataset_hashprep_report_pipeline.py (sklearn pipeline)

# Compare two datasets for drift detection
hashprep report train.csv --comparison test.csv --format html

4. List Available Checks

Discover all data quality checks that HashPrep can perform.

hashprep checks

5. Version

Check HashPrep version.

hashprep version

Available Checks

• outliers - Detect outliers using z-score
• duplicates - Find duplicate rows
• high_missing_values - Columns with high missing data
• empty_columns - Completely empty columns
• dataset_missingness - Overall missing data patterns
• missing_patterns - Correlated missing value patterns
• high_cardinality - Categorical columns with too many unique values
• single_value_columns - Constant columns with no variance
• mixed_data_types - Columns with mixed data types
• class_imbalance - Imbalanced target variable (requires --target)
• feature_correlation - Highly correlated numeric features
• categorical_correlation - Highly associated categorical features
• mixed_correlation - Numeric-categorical associations
• data_leakage - Columns identical to target
• target_leakage_patterns - Features that may leak target information
• dataset_drift - Distribution drift between datasets (requires --comparison)
• uniform_distribution - Uniformly distributed numeric columns
• unique_values - Columns where >95% values are unique
• high_zero_counts - Columns with excessive zero values
• skewness - Highly skewed numeric distributions
• infinite_values - Columns containing infinite values
• constant_length - String columns with constant character length
• extreme_text_lengths - Text columns with extreme value lengths
• datetime_skew - Datetime columns concentrated in one period
• datetime_future_dates - Datetime columns with values in the future
• datetime_gaps - Anomalous gaps in datetime sequences
• datetime_monotonicity - Non-monotonic datetime columns
• normality - Non-normal numeric distributions (Shapiro-Wilk / D'Agostino-Pearson)
• variance_homogeneity - Unequal variances across target groups (Levene's test, requires --target)
• low_mutual_information - Features with near-zero mutual information with the target (requires --target)
• empty_dataset - Empty or all-missing datasets

Python Library Usage

Basic Analysis

import pandas as pd
from hashprep import DatasetAnalyzer

# Load your dataset
df = pd.read_csv("dataset.csv")

# Create analyzer
analyzer = DatasetAnalyzer(df)

# Run analysis
summary = analyzer.analyze()

# Access results
print(f"Critical issues: {summary['critical_count']}")
print(f"Warnings: {summary['warning_count']}")

# Iterate through issues
for issue in summary['issues']:
    print(f"{issue['severity']}: {issue['description']}")

Analysis with Target Column

# Specify target for ML-specific checks
analyzer = DatasetAnalyzer(
    df,
    target_col='target_column'
)
summary = analyzer.analyze()

Run Specific Checks

# Only run specific checks
analyzer = DatasetAnalyzer(
    df,
    selected_checks=['outliers', 'high_missing_values', 'class_imbalance']
)
summary = analyzer.analyze()

Include Visualizations

# Generate analysis with plots
analyzer = DatasetAnalyzer(df, include_plots=True)
summary = analyzer.analyze()

# Plots are stored in summary['summaries']['plots']

Drift Detection

# Compare two datasets
train_df = pd.read_csv("train.csv")
test_df = pd.read_csv("test.csv")

analyzer = DatasetAnalyzer(
    train_df,
    comparison_df=test_df,
    selected_checks=['dataset_drift']
)
summary = analyzer.analyze()

Generate Reports Programmatically

from hashprep.reports import generate_report

# Analyze dataset
analyzer = DatasetAnalyzer(df, include_plots=True)
summary = analyzer.analyze()

# Generate HTML report
generate_report(
    summary,
    format='html',
    full=True,
    output_file='report.html',
    theme='minimal'
)

# Generate PDF report
generate_report(
    summary,
    format='pdf',
    full=True,
    output_file='report.pdf'
)

# Generate JSON report
generate_report(
    summary,
    format='json',
    full=True,
    output_file='report.json'
)

# Generate Markdown report
generate_report(
    summary,
    format='md',
    full=True,
    output_file='report.md'
)

Generate Fix Scripts

from hashprep.checks.core import Issue
from hashprep.preparers.codegen import CodeGenerator
from hashprep.preparers.pipeline_builder import PipelineBuilder
from hashprep.preparers.suggestions import SuggestionProvider

# After running analysis
analyzer = DatasetAnalyzer(df, target_col='target')
summary = analyzer.analyze()

# Convert issues to proper format
issues = [Issue(**i) for i in summary['issues']]
column_types = summary.get('column_types', {})

# Get suggestions
provider = SuggestionProvider(
    issues=issues,
    column_types=column_types,
    target_col='target'
)
suggestions = provider.get_suggestions()

# Generate pandas fix script
codegen = CodeGenerator(suggestions)
fixes_code = codegen.generate_pandas_script()
with open('fixes.py', 'w') as f:
    f.write(fixes_code)

# Generate sklearn pipeline
builder = PipelineBuilder(suggestions)
pipeline_code = builder.generate_pipeline_code()
with open('pipeline.py', 'w') as f:
    f.write(pipeline_code)

Load Config from File

from hashprep.utils.config_loader import load_config
from hashprep import DatasetAnalyzer

# Load thresholds from YAML, TOML, or JSON
config = load_config("hashprep.yaml")  # or .toml / .json

analyzer = DatasetAnalyzer(df, config=config)
summary = analyzer.analyze()

Example hashprep.yaml:

missing_values:
  warning: 0.3
  critical: 0.6
outliers:
  z_score: 3.5
statistical_tests:
  normality_p_value: 0.01

Only the keys you specify are overridden; all others fall back to defaults.

Custom Sampling

from hashprep.utils.sampling import SamplingConfig

# Configure sampling for large datasets
sampling_config = SamplingConfig(max_rows=10000)

analyzer = DatasetAnalyzer(
    df,
    sampling_config=sampling_config,
    auto_sample=True
)
summary = analyzer.analyze()

# Check if sampling occurred
if 'sampling_info' in summary:
    info = summary['sampling_info']
    print(f"Sampled: {info['sample_fraction']*100:.1f}%")

License

This project is licensed under the MIT License.

Contributing

We welcome contributions from the community to make HashPrep better!

Before you get started, please:

• Review our CONTRIBUTING.md for detailed guidelines and setup instructions
• Write clean, well-documented code
• Follow best practices for the stack or component you’re working on
• Open a pull request (PR) with a clear description of your changes and motivation