Phil

Phil is a representation-guided imputation library for missing tabular data.

It generates multiple imputations using a configurable strategy grid, computes Euler Characteristic Transform (ECT) descriptors over each imputed dataset, and selects the most representative imputation from the candidate set.

Installation

pip install phil

phil requires the trailed backend for ECT computation. Install it from the KRV research index or provide a compatible local build.

What Phil Does

1. Impute — runs a grid of imputation strategies (sklearn estimators or custom) over the input dataframe, producing a set of candidate datasets
2. Describe — computes an ECT descriptor for each candidate via the trailed backend
3. Select — picks the candidate closest to the mean descriptor (most representative imputation)
4. Transform — exposes the fitted pipeline for inference on new data

Quick Start

import pandas as pd
from phil import Phil

df = pd.read_csv("data_with_missing.csv")

phil = Phil(samples=30, random_state=42)
imputed_df = phil.fit(df)

# Apply the same fitted pipeline to new data
new_df = phil.transform(new_data)

scikit-learn Pipeline Integration

from sklearn.pipeline import Pipeline
from sklearn.ensemble import RandomForestClassifier
from phil import PhilTransformer

pipe = Pipeline([
    ("imputer", PhilTransformer(samples=20, random_state=0)),
    ("model", RandomForestClassifier()),
])
pipe.fit(X_train, y_train)

Configuration

Imputation grids

Phil ships with named grids accessible via GridGallery:

Name	Methods
default	BayesianRidge, DecisionTree, RandomForest, GradientBoosting
sampling	DistributionImputer (empirical sampling)
finance	IterativeImputer, KNNImputer, SimpleImputer
healthcare	KNNImputer, SimpleImputer, IterativeImputer
marketing	SimpleImputer, KNNImputer, IterativeImputer
engineering	SimpleImputer, KNNImputer, IterativeImputer

Pass a grid name or an ImputationConfig directly:

from phil import Phil, ImputationConfig
from sklearn.model_selection import ParameterGrid

config = ImputationConfig(
    methods=["KNNImputer"],
    modules=["sklearn.impute"],
    grids=[ParameterGrid({"n_neighbors": [3, 5, 7]})],
)
phil = Phil(param_grid=config)

ECT descriptor

ECT is configured via ECTConfig:

from phil import Phil, ECTConfig

ect_config = ECTConfig(
    num_thetas=64,
    radius=1.0,
    resolution=100,
    scale=500,
    normalize=True,
    seed=42,
)
phil = Phil(config=ect_config)

Development

uv sync --all-extras
uv run pytest -v
uv run black phil/ tests/

Documentation

Project documentation lives under docs/source with unified API and guide pages. Build locally with uv run sphinx-build -M html docs/source docs/build.