Imperfekt - Understanding Data Imperfections in Time-Series

A comprehensive analysis toolkit for studying "imperfect" data patterns in time-series datasets. Imperfection refers to missingness, implausible values, irregular sampling, and other data quality issues that can be indicated using a binary mask.

Overview

This library provides tools to analyze data quality issues in time-series data, including:

• Preliminary analysis of the observed values (description, normality, correlation)
• Irregularity analysis of the observation time grid (intervals, burstiness, dominant frequency)
• Intravariable analysis of imperfection patterns for individual variables
• Intervariable analysis of co-occurring imperfections across multiple parameters
• Group- and event-based analysis to compare imperfection between cohorts or around events
• Case-level metrics and stratification to rank and bucket individual cases by imperfection
• Feature generation based on imperfection patterns for downstream ML tasks

Two imperfection types are supported: "missingness" (nulls) and "plausibility" (values flagged as implausible via IQR/MAD bounds or explicit reference ranges).

Installation

Install the library using pip:

pip install imperfekt

Note: Plots are drawn with matplotlib by default. If you switch to Plotly (plot_library="plotly") and export figures as static images (save_results=True), some environments may raise a plotly_get_chrome/Kaleido error at runtime. This happens because Kaleido needs a Chrome/Chromium binary. Install Chrome manually, or run:

plotly_get_chrome

Quick Start

import polars as pl
from imperfekt import Imperfekt, FeatureGenerator

# Load your time-series data
df = pl.read_parquet("your_data.parquet")

# Configure Analyzer Setup
analyzer = Imperfekt(
    df=df,
    id_col="id",  # Unique identifier column
    clock_col="clock",  # Timestamp column
    cols=["var1", "var2"],  # Variables to analyze
    save_path="./results",
    imperfection="missingness",  # or "plausibility"
)

# Simple intravariable imperfection stats
analyzer.intravariable.column_statistics(save_results=True)
print(analyzer.intravariable.results.cs_overall_statistics)
print(analyzer.intravariable.results.cs_case_level_statistics)

# Run full imperfection analysis (preliminary, irregularity, intra- and intervariable analyses)
analyzer.run()  # cheap_mode=True for a faster, reduced set of analyses

# Compare imperfection between groups/labels, or around events
analyzer.run_grouped_analysis(annotation_col="age")
analyzer.run_event_based_analysis(events_df=events_df, window_size=300)

# Or generate imperfection-aware features for ML
fg = FeatureGenerator(df=df, id_col="id", clock_col="clock", variable_cols=["var1", "var2"])
features_df = fg.add_binary_masks().add_temporal_features().df

# Or restrict individual steps to a subset of variables
features_df = (
    fg.add_binary_masks(cols=["var1"])
    .add_temporal_features(cols=["var1"])
    .add_window_features(rolling_window_sizes=[2], ewma_alphas=[0.3], cols=["var1", "var2"])
    .df
)

# Or generate everything at once
features_df = fg.generate_all_features()

Runnable end-to-end scripts live in examples/scripts/.

Library Structure

imperfekt/
├── analysis/
│   ├── preliminary/     # Basic data exploration
│   ├── irregularity/    # Observation-grid irregularity
│   ├── intravariable/   # Single variable analysis
│   ├── intervariable/   # Multi-variable patterns
│   └── utils/           # Shared utilities (masking, statistics, stratification, plotting)
├── features/            # Feature engineering
│   ├── core.py          # FeatureGenerator class
│   ├── temporal.py      # Time-based features
│   ├── window.py        # Rolling and EWMA features
│   ├── irregularity.py  # Sampling-rhythm features
│   └── interaction.py   # Variable interactions
└── config/              # Default settings

Module-level documentation: analysis/intravariable/README.md, analysis/intervariable/README.md, analysis/irregularity/README.md, features/README.md.

Data Format

The library expects time-series data with the following structure:

Key Dependencies

• polars: High-performance data processing
• matplotlib / plotly: Static and interactive visualizations
• statsmodels, pingouin, scikit-posthocs: Statistical computations

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

AI Disclaimer

We used AI (Google Gemini 3.1 Pro, Anthropic Claude Opus 5) during the development of this repository. All AI-generated output was reviewed by the authors, who take full responsibility for the code.

License

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