Source code for evalml.pipelines.pipeline_base

import copy
import inspect
import os
import re
import sys
import traceback
from abc import ABC, abstractmethod
from collections import OrderedDict

import cloudpickle
import pandas as pd

from .components import (
    PCA,
    DFSTransformer,
    Estimator,
    LinearDiscriminantAnalysis,
    StackedEnsembleClassifier,
    StackedEnsembleRegressor
)
from .components.utils import all_components, handle_component_class

from evalml.exceptions import (
    IllFormattedClassNameError,
    ObjectiveCreationError,
    PipelineScoreError
)
from evalml.objectives import get_objective
from evalml.pipelines import ComponentGraph
from evalml.pipelines.pipeline_meta import PipelineBaseMeta
from evalml.problem_types import is_binary
from evalml.utils import (
    classproperty,
    get_logger,
    import_or_raise,
    infer_feature_types,
    jupyter_check,
    log_subtitle,
    log_title,
    safe_repr
)

logger = get_logger(__file__)


[docs]class PipelineBase(ABC, metaclass=PipelineBaseMeta): """Base class for all pipelines.""" @property @classmethod @abstractmethod def component_graph(cls): """Returns list or dictionary of components representing pipeline graph structure Returns: list(str / ComponentBase subclass): List of ComponentBase subclasses or strings denotes graph structure of this pipeline. """ custom_hyperparameters = None custom_name = None problem_type = None
[docs] def __init__(self, parameters, random_seed=0): """Machine learning pipeline made out of transformers and a estimator. Required Class Variables: component_graph (list or dict): List of components in order. Accepts strings or ComponentBase subclasses in the list. Note that when duplicate components are specified in a list, the duplicate component names will be modified with the component's index in the list. For example, the component graph [Imputer, One Hot Encoder, Imputer, Logistic Regression Classifier] will have names ["Imputer", "One Hot Encoder", "Imputer_2", "Logistic Regression Classifier"] Arguments: parameters (dict): Dictionary with component names as keys and dictionary of that component's parameters as values. An empty dictionary {} implies using all default values for component parameters. random_seed (int): Seed for the random number generator. Defaults to 0. """ self.random_seed = random_seed if isinstance(self.component_graph, list): # Backwards compatibility self._component_graph = ComponentGraph().from_list(self.component_graph, random_seed=self.random_seed) else: self._component_graph = ComponentGraph(component_dict=self.component_graph, random_seed=self.random_seed) self._component_graph.instantiate(parameters) self.input_feature_names = {} self.input_target_name = None final_component = self._component_graph.get_last_component() self.estimator = final_component if isinstance(final_component, Estimator) else None self._estimator_name = self._component_graph.compute_order[-1] if self.estimator is not None else None self._validate_estimator_problem_type() self._is_fitted = False self._pipeline_params = parameters.get("pipeline", {})
@classproperty def name(cls): """Returns a name describing the pipeline. By default, this will take the class name and add a space between each capitalized word (class name should be in Pascal Case). If the pipeline has a custom_name attribute, this will be returned instead. """ if cls.custom_name: name = cls.custom_name else: rex = re.compile(r'(?<=[a-z])(?=[A-Z])') name = rex.sub(' ', cls.__name__) if name == cls.__name__: raise IllFormattedClassNameError("Pipeline Class {} needs to follow Pascal Case standards or `custom_name` must be defined.".format(cls.__name__)) return name @classproperty def summary(cls): """Returns a short summary of the pipeline structure, describing the list of components used. Example: Logistic Regression Classifier w/ Simple Imputer + One Hot Encoder """ component_graph = [handle_component_class(component_class) for _, component_class in copy.copy(cls.linearized_component_graph)] if len(component_graph) == 0: return "Empty Pipeline" summary = "Pipeline" component_graph[-1] = component_graph[-1] if inspect.isclass(component_graph[-1]) and issubclass(component_graph[-1], Estimator): estimator_class = component_graph.pop(-1) summary = estimator_class.name if len(component_graph) == 0: return summary component_names = [component_class.name for component_class in component_graph] return '{} w/ {}'.format(summary, ' + '.join(component_names)) @classproperty def linearized_component_graph(cls): """Returns a component graph in list form. Note: this is not guaranteed to be in proper component computation order""" return ComponentGraph.linearized_component_graph(cls.component_graph) def _validate_estimator_problem_type(self): """Validates this pipeline's problem_type against that of the estimator from `self.component_graph`""" if self.estimator is None: # Allow for pipelines that do not end with an estimator return estimator_problem_types = self.estimator.supported_problem_types if self.problem_type not in estimator_problem_types: raise ValueError("Problem type {} not valid for this component graph. Valid problem types include {}." .format(self.problem_type, estimator_problem_types)) def __getitem__(self, index): if isinstance(index, slice): raise NotImplementedError('Slicing pipelines is currently not supported.') return self._component_graph[index] def __setitem__(self, index, value): raise NotImplementedError('Setting pipeline components is not supported.')
[docs] def get_component(self, name): """Returns component by name Arguments: name (str): Name of component Returns: Component: Component to return """ return self._component_graph.get_component(name)
[docs] def describe(self, return_dict=False): """Outputs pipeline details including component parameters Arguments: return_dict (bool): If True, return dictionary of information about pipeline. Defaults to False. Returns: dict: Dictionary of all component parameters if return_dict is True, else None """ log_title(logger, self.name) logger.info("Problem Type: {}".format(self.problem_type)) logger.info("Model Family: {}".format(str(self.model_family))) if self._estimator_name in self.input_feature_names: logger.info("Number of features: {}".format(len(self.input_feature_names[self._estimator_name]))) # Summary of steps log_subtitle(logger, "Pipeline Steps") pipeline_dict = { "name": self.name, "problem_type": self.problem_type, "model_family": self.model_family, "components": dict() } for number, component in enumerate(self._component_graph, 1): component_string = str(number) + ". " + component.name logger.info(component_string) pipeline_dict["components"].update({component.name: component.describe(print_name=False, return_dict=return_dict)}) if return_dict: return pipeline_dict
[docs] def compute_estimator_features(self, X, y=None): """Transforms the data by applying all pre-processing components. Arguments: X (ww.DataTable, pd.DataFrame): Input data to the pipeline to transform. Returns: ww.DataTable: New transformed features. """ X_t = self._component_graph.compute_final_component_features(X, y=y) return X_t
def _compute_features_during_fit(self, X, y): self.input_target_name = y.name X_t = self._component_graph.fit_features(X, y) self.input_feature_names = self._component_graph.input_feature_names return X_t def _fit(self, X, y): self.input_target_name = y.name self._component_graph.fit(X, y) self.input_feature_names = self._component_graph.input_feature_names
[docs] @abstractmethod def fit(self, X, y): """Build a model Arguments: X (ww.DataTable, pd.DataFrame or np.ndarray): The input training data of shape [n_samples, n_features] y (ww.DataColumn, pd.Series, np.ndarray): The target training data of length [n_samples] Returns: self """
[docs] def predict(self, X, objective=None): """Make predictions using selected features. Arguments: X (ww.DataTable, pd.DataFrame, or np.ndarray): Data of shape [n_samples, n_features] objective (Object or string): The objective to use to make predictions Returns: ww.DataColumn: Predicted values. """ X = infer_feature_types(X) predictions = self._component_graph.predict(X) predictions_series = predictions.to_series() predictions_series.name = self.input_target_name return infer_feature_types(predictions_series)
[docs] @abstractmethod def score(self, X, y, objectives): """Evaluate model performance on current and additional objectives Arguments: X (ww.DataTable, pd.DataFrame or np.ndarray): Data of shape [n_samples, n_features] y (pd.Series, ww.DataColumn, or np.ndarray): True labels of length [n_samples] objectives (list): Non-empty list of objectives to score on Returns: dict: Ordered dictionary of objective scores """
@staticmethod def _score(X, y, predictions, objective): return objective.score(y, predictions, X) def _score_all_objectives(self, X, y, y_pred, y_pred_proba, objectives): """Given data, model predictions or predicted probabilities computed on the data, and an objective, evaluate and return the objective score. Will raise a PipelineScoreError if any objectives fail. Arguments: X (pd.DataFrame): The feature matrix. y (pd.Series): The target data. y_pred (pd.Series): The pipeline predictions. y_pred_proba (pd.Dataframe, pd.Series, None): The predicted probabilities for classification problems. Will be a DataFrame for multiclass problems and Series otherwise. Will be None for regression problems. objectives (list): List of objectives to score. Returns: dict: Ordered dictionary with objectives and their scores. """ scored_successfully = OrderedDict() exceptions = OrderedDict() for objective in objectives: try: if not objective.is_defined_for_problem_type(self.problem_type): raise ValueError(f'Invalid objective {objective.name} specified for problem type {self.problem_type}') y_pred = self._select_y_pred_for_score(X, y, y_pred, y_pred_proba, objective) score = self._score(X, y, y_pred_proba if objective.score_needs_proba else y_pred, objective) scored_successfully.update({objective.name: score}) except Exception as e: tb = traceback.format_tb(sys.exc_info()[2]) exceptions[objective.name] = (e, tb) if exceptions: # If any objective failed, throw an PipelineScoreError raise PipelineScoreError(exceptions, scored_successfully) # No objectives failed, return the scores return scored_successfully def _select_y_pred_for_score(self, X, y, y_pred, y_pred_proba, objective): return y_pred @classproperty def model_family(cls): """Returns model family of this pipeline template""" component_graph = copy.copy(cls.component_graph) if isinstance(component_graph, list): return handle_component_class(component_graph[-1]).model_family else: order = ComponentGraph.generate_order(component_graph) final_component = order[-1] return handle_component_class(component_graph[final_component][0]).model_family @classproperty def hyperparameters(cls): """Returns hyperparameter ranges from all components as a dictionary""" hyperparameter_ranges = dict() for component_name, component_class in cls.linearized_component_graph: component_hyperparameters = copy.copy(component_class.hyperparameter_ranges) if cls.custom_hyperparameters and component_name in cls.custom_hyperparameters: component_hyperparameters.update(cls.custom_hyperparameters.get(component_name, {})) hyperparameter_ranges[component_name] = component_hyperparameters return hyperparameter_ranges @property def parameters(self): """Returns parameter dictionary for this pipeline Returns: dict: Dictionary of all component parameters """ components = [(component_name, component_class) for component_name, component_class in self._component_graph.component_instances.items()] component_parameters = {c_name: copy.copy(c.parameters) for c_name, c in components if c.parameters} if self._pipeline_params: component_parameters['pipeline'] = self._pipeline_params return component_parameters @classproperty def default_parameters(cls): """Returns the default parameter dictionary for this pipeline. Returns: dict: Dictionary of all component default parameters. """ defaults = {} for c in cls.component_graph: component = handle_component_class(c) if component.default_parameters: defaults[component.name] = component.default_parameters return defaults @property def feature_importance(self): """Return importance associated with each feature. Features dropped by the feature selection are excluded. Returns: pd.DataFrame including feature names and their corresponding importance """ feature_names = self.input_feature_names[self._estimator_name] importance = list(zip(feature_names, self.estimator.feature_importance)) # note: this only works for binary importance.sort(key=lambda x: -abs(x[1])) df = pd.DataFrame(importance, columns=["feature", "importance"]) return df
[docs] def graph(self, filepath=None): """Generate an image representing the pipeline graph Arguments: filepath (str, optional): Path to where the graph should be saved. If set to None (as by default), the graph will not be saved. Returns: graphviz.Digraph: Graph object that can be directly displayed in Jupyter notebooks. """ graphviz = import_or_raise('graphviz', error_msg='Please install graphviz to visualize pipelines.') # Try rendering a dummy graph to see if a working backend is installed try: graphviz.Digraph().pipe() except graphviz.backend.ExecutableNotFound: raise RuntimeError( "To graph entity sets, a graphviz backend is required.\n" + "Install the backend using one of the following commands:\n" + " Mac OS: brew install graphviz\n" + " Linux (Ubuntu): sudo apt-get install graphviz\n" + " Windows: conda install python-graphviz\n" ) graph_format = None path_and_name = None if filepath: # Explicitly cast to str in case a Path object was passed in filepath = str(filepath) try: f = open(filepath, 'w') f.close() except (IOError, FileNotFoundError): raise ValueError(('Specified filepath is not writeable: {}'.format(filepath))) path_and_name, graph_format = os.path.splitext(filepath) graph_format = graph_format[1:].lower() # ignore the dot supported_filetypes = graphviz.backend.FORMATS if graph_format not in supported_filetypes: raise ValueError(("Unknown format '{}'. Make sure your format is one of the " + "following: {}").format(graph_format, supported_filetypes)) graph = self._component_graph.graph(path_and_name, graph_format) if filepath: graph.render(path_and_name, cleanup=True) return graph
[docs] def graph_feature_importance(self, importance_threshold=0): """Generate a bar graph of the pipeline's feature importance Arguments: importance_threshold (float, optional): If provided, graph features with a permutation importance whose absolute value is larger than importance_threshold. Defaults to zero. Returns: plotly.Figure, a bar graph showing features and their corresponding importance """ go = import_or_raise("plotly.graph_objects", error_msg="Cannot find dependency plotly.graph_objects") if jupyter_check(): import_or_raise("ipywidgets", warning=True) feat_imp = self.feature_importance feat_imp['importance'] = abs(feat_imp['importance']) if importance_threshold < 0: raise ValueError(f'Provided importance threshold of {importance_threshold} must be greater than or equal to 0') # Remove features with importance whose absolute value is less than importance threshold feat_imp = feat_imp[feat_imp['importance'] >= importance_threshold] # List is reversed to go from ascending order to descending order feat_imp = feat_imp.iloc[::-1] title = 'Feature Importance' subtitle = 'May display fewer features due to feature selection' data = [go.Bar( x=feat_imp['importance'], y=feat_imp['feature'], orientation='h' )] layout = { 'title': '{0}<br><sub>{1}</sub>'.format(title, subtitle), 'height': 800, 'xaxis_title': 'Feature Importance', 'yaxis_title': 'Feature', 'yaxis': { 'type': 'category' } } fig = go.Figure(data=data, layout=layout) return fig
[docs] def save(self, file_path, pickle_protocol=cloudpickle.DEFAULT_PROTOCOL): """Saves pipeline at file path Arguments: file_path (str): location to save file pickle_protocol (int): the pickle data stream format. Returns: None """ with open(file_path, 'wb') as f: cloudpickle.dump(self, f, protocol=pickle_protocol)
[docs] @staticmethod def load(file_path): """Loads pipeline at file path Arguments: file_path (str): location to load file Returns: PipelineBase object """ with open(file_path, 'rb') as f: return cloudpickle.load(f)
[docs] def clone(self): """Constructs a new pipeline with the same components, parameters, and random state. Returns: A new instance of this pipeline with identical components, parameters, and random state. """ return self.__class__(self.parameters, random_seed=self.random_seed)
def __eq__(self, other): if not isinstance(other, self.__class__): return False random_seed_eq = self.random_seed == other.random_seed if not random_seed_eq: return False attributes_to_check = ['parameters', '_is_fitted', 'component_graph', 'input_feature_names', 'input_target_name'] for attribute in attributes_to_check: if getattr(self, attribute) != getattr(other, attribute): return False return True def __str__(self): return self.name def __repr__(self): def repr_component(parameters): return ', '.join([f"'{key}': {safe_repr(value)}" for key, value in parameters.items()]) parameters_repr = ' '.join([f"'{component}':{{{repr_component(parameters)}}}," for component, parameters in self.parameters.items()]) return f'{(type(self).__name__)}(parameters={{{parameters_repr}}})' def __iter__(self): return self def __next__(self): return next(self._component_graph) def _get_feature_provenance(self): return self._component_graph._feature_provenance @property def _supports_fast_permutation_importance(self): has_more_than_one_estimator = sum(isinstance(c, Estimator) for c in self._component_graph) > 1 _all_components = set(all_components()) has_custom_components = any(c.__class__ not in _all_components for c in self._component_graph) has_dim_reduction = any(isinstance(c, (PCA, LinearDiscriminantAnalysis)) for c in self._component_graph) has_dfs = any(isinstance(c, DFSTransformer) for c in self._component_graph) has_stacked_ensembler = any(isinstance(c, (StackedEnsembleClassifier, StackedEnsembleRegressor)) for c in self._component_graph) return not any([has_more_than_one_estimator, has_custom_components, has_dim_reduction, has_dfs, has_stacked_ensembler])
[docs] @staticmethod def create_objectives(objectives): objective_instances = [] for objective in objectives: try: objective_instances.append(get_objective(objective, return_instance=True)) except ObjectiveCreationError as e: msg = f"Cannot pass {objective} as a string in pipeline.score. Instantiate first and then add it to the list of objectives." raise ObjectiveCreationError(msg) from e return objective_instances
[docs] def can_tune_threshold_with_objective(self, objective): """Determine whether the threshold of a binary classification pipeline can be tuned. Arguments: pipeline (PipelineBase): Binary classification pipeline. objective (ObjectiveBase): Primary AutoMLSearch objective. Returns: bool: True if the pipeline threshold can be tuned. """ return is_binary(self.problem_type) and objective.is_defined_for_problem_type(self.problem_type) and objective.can_optimize_threshold