"""
Module that provides the TreeExplainer class base on the Baseexplainer class
"""
import os
import tempfile
from typing import Optional, List, Dict, Union
import numpy as np
import pandas as pd
import sklearn
from subprocess import call
from sklearn import tree
from trelawney.base_explainer import BaseExplainer
[docs]class TreeExplainer(BaseExplainer):
"""
The TreeExplainer class is composed of 4 methods:
- fit: get the right model
- feature_importance (global interpretation)
- explain_local (local interpretation, WIP)
- plot_tree (full tree visualisation)
"""
def __init__(self, class_names: Optional[List[str]] = None):
"""
initialize class_names, categorical_features and model_to_explain
"""
self.class_names = class_names
self._model_to_explain = None
self._feature_names = None
[docs] def fit(self, model: sklearn.base.BaseEstimator, x_train: Union[pd.Series, pd.DataFrame, np.ndarray],
y_train: pd.DataFrame):
x_train = self._get_dataframe_from_mixed_input(x_train)
self._model_to_explain = model
self._feature_names = x_train.columns
return self
[docs] def feature_importance(self, x_explain: Union[pd.Series, pd.DataFrame, np.ndarray], n_cols: Optional[int] = None) -> Dict[str, float]:
"""
returns a relative importance of each feature globally as a dict.
:param x_explain: the dataset to explain on
:param n_cols: the maximum number of features to return
"""
x_explain = self._get_dataframe_from_mixed_input(x_explain)
res = dict(zip(x_explain.columns, self._model_to_explain.feature_importances_))
return res
[docs] def explain_local(self, x_explain: Union[pd.Series, pd.DataFrame, np.ndarray],
n_cols: Optional[int] = None) -> List[Dict[str, float]]:
"""
returns local relative importance of features for a specific observation.
:param x_explain: the dataset to explain on
:param n_cols: the maximum number of features to return
"""
raise NotImplementedError('no consensus on which values can explain the path followed by an observation')
[docs] def plot_tree(self, out_path: str = './tree_viz'):
"""
creates a png file of the tree saved in out_path
:param out_path: the path to save the png representation of the tree to
"""
tree.export_graphviz(self._model_to_explain, out_file=out_path + '.dot', filled=True, rounded=True,
special_characters=True, feature_names=self._feature_names, class_names=self.class_names)
call(['dot', '-Tpng', out_path + '.dot', '-o', out_path + '.png', '-Gdpi=600'])