[ENH] log-normal AFT model from lifelines (#258)

Adds the log-normal AFT model from `lifelines`.

Towards #250

docs/source/api_reference/survival.rst

@@ -99,6 +99,7 @@ Accelerated failure time models
     :toctree: auto_generated/
     :template: class.rst
 
+    AFTLogNormal
     AFTWeibull
 
 Generalized additive survival models

skpro/survival/aft/__init__.py

@@ -1,6 +1,7 @@
 """Module containing accelerated failure time models."""
 # copyright: skpro developers, BSD-3-Clause License (see LICENSE file)
 
-__all__ = ["AFTWeibull"]
+__all__ = ["AFTLogNormal", "AFTWeibull"]
 
+from skpro.survival.aft._aft_lifelines_lognormal import AFTLogNormal
 from skpro.survival.aft._aft_lifelines_weibull import AFTWeibull

skpro/survival/aft/_aft_lifelines_lognormal.py

@@ -0,0 +1,209 @@
+"""Interface adapter to lifelines Log-Normal AFT model."""
+# copyright: skpro developers, BSD-3-Clause License (see LICENSE file)
+
+__author__ = ["fkiraly"]
+
+import numpy as np
+
+from skpro.distributions.lognormal import LogNormal
+from skpro.survival.adapters.lifelines import _LifelinesAdapter
+from skpro.survival.base import BaseSurvReg
+
+
+class AFTLogNormal(_LifelinesAdapter, BaseSurvReg):
+    r"""Log-Normal AFT model, from lifelines.
+
+    Direct interface to ``lifelines.fitters.LogNormalAFTFitter``,
+    by ``CamDavidsonPilon``.
+
+    This class implements a Log-Normal AFT model. The model has parametric form, with
+    :math:`\mu(x) = \exp\left(\beta_0 + \beta_1x_1 + ... + \beta_n x_n \right)`,
+    and optionally,
+    :math:`\sigma(y) = \exp\left(\alpha_0 + \alpha_1 y_1 + ... + \alpha_m y_m \right)`,
+
+    with predictive distribution being Log-Normal, with
+    mean :math:`\mu(x)` and standard deviation :math:`\sigma(y)`.
+
+    Parameters
+    ----------
+    mu_cols: pd.Index or coercible, optional, default=None
+        Columns of the input data frame to be used as covariates for
+        the mean parameter :math:`\mu`.
+        If None, all columns are used.
+
+    sd_cols: string "all", pd.Index or coercible, optional, default=None
+        Columns of the input data frame to be used as covariates for
+        the standard deviation parameter :math:`\sigma`.
+        If None, no covariates are used, the standard deviation parameter
+        is estimated as a constant. If "all", all columns are used.
+
+    fit_intercept: boolean, optional (default=True)
+        Whether to fit an intercept term in the model.
+
+    alpha: float, optional (default=0.05)
+      the level in the confidence intervals around the estimated survival function,
+      for computation of ``confidence_intervals_`` fitted parameter.
+
+    penalizer: float or array, optional (default=0.0)
+        the penalizer coefficient to the size of the coefficients.
+        See ``l1_ratio``. Must be equal to or greater than 0.
+        Alternatively, penalizer is an array equal in size to the number of parameters,
+        with penalty coefficients for specific variables. For
+        example, ``penalizer=0.01 * np.ones(p)`` is the same as ``penalizer=0.01``
+
+    l1_ratio: float, optional (default=0.0)
+        how much of the penalizer should be attributed to an l1 penalty
+        (otherwise an l2 penalty). The penalty function looks like
+        ``penalizer * l1_ratio * ||w||_1 + 0.5 * penalizer * (1 - l1_ratio) * ||w||^2_2``  # noqa E501
+
+    Attributes
+    ----------
+    params_ : DataFrame
+        The estimated coefficients
+    confidence_intervals_ : DataFrame
+        The lower and upper confidence intervals for the coefficients
+    durations: Series
+        The event_observed variable provided
+    event_observed: Series
+        The event_observed variable provided
+    weights: Series
+        The event_observed variable provided
+    variance_matrix_ : DataFrame
+        The variance matrix of the coefficients
+    standard_errors_: Series
+        the standard errors of the estimates
+    score_: float
+        the concordance index of the model.
+    """
+
+    _tags = {"authors": ["CamDavidsonPilon", "fkiraly"]}
+    # CamDavidsonPilon, credit for interfaced estimator
+
+    def __init__(
+        self,
+        mu_cols=None,
+        sd_cols=None,
+        fit_intercept: bool = True,
+        alpha: float = 0.05,
+        penalizer: float = 0.0,
+        l1_ratio: float = 0.0,
+    ):
+        self.mu_cols = mu_cols
+        self.sd_cols = sd_cols
+        self.alpha = alpha
+        self.penalizer = penalizer
+        self.l1_ratio = l1_ratio
+        self.fit_intercept = fit_intercept
+
+        super().__init__()
+
+        if mu_cols is not None:
+            self.X_col_subset = mu_cols
+
+    def _get_lifelines_class(self):
+        """Getter of the lifelines class to be used for the adapter."""
+        from lifelines.fitters.weibull_aft_fitter import WeibullAFTFitter
+
+        return WeibullAFTFitter
+
+    def _get_lifelines_object(self):
+        """Abstract method to initialize lifelines object.
+
+        The default initializes result of _get_lifelines_class
+        with self.get_params.
+        """
+        cls = self._get_lifelines_class()
+        params = self.get_params()
+        params.pop("mu_cols", None)
+        params.pop("sd_cols", None)
+        return cls(**params)
+
+    def _add_extra_fit_args(self, X, y, C=None):
+        """Get extra arguments for the fit method.
+
+        Parameters
+        ----------
+        X : pd.DataFrame
+            Training features
+        y: pd.DataFrame
+            Training labels
+        C: pd.DataFrame, optional (default=None)
+            Censoring information for survival analysis.
+        fit_args: dict, optional (default=None)
+            Existing arguments for the fit method, from the adapter.
+
+        Returns
+        -------
+        dict
+            Extra arguments for the fit method.
+        """
+        if self.mu_cols is not None:
+            if self.mu_cols == "all":
+                return {"ancillary": True}
+            else:
+                return {"ancillary": X[self.mu_cols]}
+        else:
+            return {}
+
+    def _predict_proba(self, X):
+        """Predict_proba method adapter.
+
+        Parameters
+        ----------
+        X : pd.DataFrame
+            Features to predict on.
+
+        Returns
+        -------
+        skpro Empirical distribution
+        """
+        if self.sd_cols == "all":
+            ancillary = X
+        elif self.sd_cols is not None:
+            ancillary = X[self.sd_cols]
+        else:
+            ancillary = None
+
+        if self.mu_cols is not None:
+            df = X[self.mu_cols]
+        else:
+            df = X
+
+        lifelines_est = getattr(self, self._estimator_attr)
+        ll_pred_proba = lifelines_est._prep_inputs_for_prediction_and_return_scores
+
+        mu, sigma = ll_pred_proba(df, ancillary)
+        mu = np.expand_dims(mu, axis=1)
+        sigma = np.expand_dims(sigma, axis=1)
+
+        dist = LogNormal(mu=mu, sigma=sigma, index=X.index, columns=self._y_cols)
+        return dist
+
+    @classmethod
+    def get_test_params(cls, parameter_set="default"):
+        """Return testing parameter settings for the estimator.
+
+        Parameters
+        ----------
+        parameter_set : str, default="default"
+            Name of the set of test parameters to return, for use in tests. If no
+            special parameters are defined for a value, will return `"default"` set.
+
+        Returns
+        -------
+        params : dict or list of dict, default = {}
+            Parameters to create testing instances of the class
+            Each dict are parameters to construct an "interesting" test instance, i.e.,
+            `MyClass(**params)` or `MyClass(**params[i])` creates a valid test instance.
+            `create_test_instance` uses the first (or only) dictionary in `params`
+        """
+        params1 = {}
+
+        params2 = {
+            "sd_cols": "all",
+            "fit_intercept": False,
+            "alpha": 0.1,
+            "penalizer": 0.1,
+            "l1_ratio": 0.1,
+        }
+        return [params1, params2]