ae_model.py

"""Shared autoencoder wrapper class for pickle compatibility."""
import numpy as np
import torch
import torch.nn as nn
import pandas as pd


class Autoencoder(nn.Module):
    def __init__(self, input_dim):
        super().__init__()
        self.encoder = nn.Sequential(
            nn.Linear(input_dim, 64), nn.ReLU(), nn.Dropout(0.2),
            nn.Linear(64, 32), nn.ReLU(),
            nn.Linear(32, 16), nn.ReLU()
        )
        self.decoder = nn.Sequential(
            nn.Linear(16, 32), nn.ReLU(), nn.Dropout(0.2),
            nn.Linear(32, 64), nn.ReLU(),
            nn.Linear(64, input_dim)
        )
    
    def forward(self, x):
        return self.decoder(self.encoder(x))


class AutoencoderWrapper:
    """Wrapper to make autoencoder compatible with sklearn interface."""
    def __init__(self, model):
        self.model = model
        self.classes_ = np.array([0, 1])
    
    def predict_proba(self, X):
        self.model.eval()
        Xn = X.values if isinstance(X, pd.DataFrame) else X
        with torch.no_grad():
            Xt = torch.FloatTensor(Xn)
            out = self.model(Xt)
            re = torch.mean((out - Xt)**2, dim=1).numpy()
        scores = 1 / (1 + np.exp(-10 * (re - np.median(re))))
        return np.column_stack([1-scores, scores])
    
    def predict(self, X, threshold=0.5):
        return (self.predict_proba(X)[:, 1] >= threshold).astype(int)