"""An automl algorithm which first fits a base round of pipelines with default parameters, then does a round of parameter tuning on each pipeline in order of performance."""
import inspect
import logging
import warnings
from operator import itemgetter
import numpy as np
from skopt.space import Categorical, Integer, Real
from .automl_algorithm import AutoMLAlgorithm, AutoMLAlgorithmException
from evalml.automl.utils import get_pipelines_from_component_graphs
from evalml.exceptions import ParameterNotUsedWarning
from evalml.model_family import ModelFamily
from evalml.pipelines.components.utils import get_estimators
from evalml.pipelines.utils import make_pipeline
from evalml.problem_types import is_multiclass
from evalml.utils import infer_feature_types
from evalml.utils.logger import get_logger
_ESTIMATOR_FAMILY_ORDER = [
ModelFamily.LINEAR_MODEL,
ModelFamily.XGBOOST,
ModelFamily.LIGHTGBM,
ModelFamily.CATBOOST,
ModelFamily.RANDOM_FOREST,
ModelFamily.DECISION_TREE,
ModelFamily.EXTRA_TREES,
ModelFamily.ARIMA,
]
[docs]class IterativeAlgorithm(AutoMLAlgorithm):
"""An automl algorithm which first fits a base round of pipelines with default parameters, then does a round of parameter tuning on each pipeline in order of performance.
Args:
X (pd.DataFrame): Training data.
y (pd.Series): Target data.
problem_type (ProblemType): Problem type associated with training data.
sampler_name (BaseSampler): Sampler to use for preprocessing. Defaults to None.
allowed_model_families (list(str, ModelFamily)): The model families to search. The default of None searches over all
model families. Run evalml.pipelines.components.utils.allowed_model_families("binary") to see options. Change `binary`
to `multiclass` or `regression` depending on the problem type. Note that if allowed_pipelines is provided,
this parameter will be ignored.
allowed_component_graphs (dict): A dictionary of lists or ComponentGraphs indicating the component graphs allowed in the search.
The format should follow { "Name_0": [list_of_components], "Name_1": [ComponentGraph(...)] }
The default of None indicates all pipeline component graphs for this problem type are allowed. Setting this field will cause
allowed_model_families to be ignored.
e.g. allowed_component_graphs = { "My_Graph": ["Imputer", "One Hot Encoder", "Random Forest Classifier"] }
max_batches (int): The maximum number of batches to be evaluated. Used to determine ensembling. Defaults to None.
max_iterations (int): The maximum number of iterations to be evaluated. Used to determine ensembling. Defaults to None.
tuner_class (class): A subclass of Tuner, to be used to find parameters for each pipeline. The default of None indicates the SKOptTuner will be used.
random_seed (int): Seed for the random number generator. Defaults to 0.
pipelines_per_batch (int): The number of pipelines to be evaluated in each batch, after the first batch. Defaults to 5.
n_jobs (int or None): Non-negative integer describing level of parallelism used for pipelines. Defaults to None.
number_features (int): The number of columns in the input features. Defaults to None.
ensembling (boolean): If True, runs ensembling in a separate batch after every allowed pipeline class has been iterated over. Defaults to False.
text_in_ensembling (boolean): If True and ensembling is True, then n_jobs will be set to 1 to avoid downstream sklearn stacking issues related to nltk. Defaults to False.
pipeline_params (dict or None): Pipeline-level parameters that should be passed to the proposed pipelines. Defaults to None.
custom_hyperparameters (dict or None): Custom hyperparameter ranges specified for pipelines to iterate over. Defaults to None.
_estimator_family_order (list(ModelFamily) or None): specify the sort order for the first batch. Defaults to None, which uses _ESTIMATOR_FAMILY_ORDER.
allow_long_running_models (bool): Whether or not to allow longer-running models for large multiclass problems. If False and no pipelines, component graphs, or model families are provided,
AutoMLSearch will not use Elastic Net or XGBoost when there are more than 75 multiclass targets and will not use CatBoost when there are more than 150 multiclass targets. Defaults to False.
verbose (boolean): Whether or not to display logging information regarding pipeline building. Defaults to False.
"""
def __init__(
self,
X,
y,
problem_type,
sampler_name=None,
allowed_model_families=None,
allowed_component_graphs=None,
max_batches=None,
max_iterations=None,
tuner_class=None,
random_seed=0,
pipelines_per_batch=5,
n_jobs=-1, # TODO remove
number_features=None, # TODO remove
ensembling=False,
text_in_ensembling=False,
pipeline_params=None,
custom_hyperparameters=None,
_estimator_family_order=None,
allow_long_running_models=False,
verbose=False,
):
self.X = infer_feature_types(X)
self.y = infer_feature_types(y)
self.problem_type = problem_type
self.random_seed = random_seed
self.sampler_name = sampler_name
self.allowed_model_families = allowed_model_families
self.pipelines_per_batch = pipelines_per_batch
self.n_jobs = n_jobs
self.number_features = number_features
self._first_batch_results = []
self._best_pipeline_info = {}
self.ensembling = ensembling
self._pipeline_params = pipeline_params or {}
self._custom_hyperparameters = custom_hyperparameters or {}
self.text_in_ensembling = text_in_ensembling
self.max_batches = max_batches
self.max_iterations = max_iterations
self.allow_long_running_models = allow_long_running_models
if verbose:
self.logger = get_logger(f"{__name__}.verbose")
else:
self.logger = logging.getLogger(__name__)
self._estimator_family_order = (
_estimator_family_order or _ESTIMATOR_FAMILY_ORDER
)
self.allowed_component_graphs = allowed_component_graphs
self._set_additional_pipeline_params()
self._create_pipelines()
super().__init__(
allowed_pipelines=self.allowed_pipelines,
custom_hyperparameters=custom_hyperparameters,
tuner_class=tuner_class,
text_in_ensembling=self.text_in_ensembling,
random_seed=random_seed,
n_jobs=self.n_jobs,
)
if custom_hyperparameters and not isinstance(custom_hyperparameters, dict):
raise ValueError(
f"If custom_hyperparameters provided, must be of type dict. Received {type(custom_hyperparameters)}"
)
for param_name_val in self._pipeline_params.values():
for _, param_val in param_name_val.items():
if isinstance(param_val, (Integer, Real, Categorical)):
raise ValueError(
"Pipeline parameters should not contain skopt.Space variables, please pass them "
"to custom_hyperparameters instead!"
)
for hyperparam_name_val in self._custom_hyperparameters.values():
for _, hyperparam_val in hyperparam_name_val.items():
if not isinstance(hyperparam_val, (Integer, Real, Categorical)):
raise ValueError(
"Custom hyperparameters should only contain skopt.Space variables such as Categorical, Integer,"
" and Real!"
)
def _filter_estimators(self, estimators):
"""Function to remove computationally expensive and long-running estimators from datasets with large numbers of unique classes. Thresholds were determined empirically."""
estimators_to_drop = []
if (
not is_multiclass(self.problem_type)
or self.allow_long_running_models
or self.allowed_model_families is not None
):
return estimators
unique = self.y.nunique()
if unique > 75:
estimators_to_drop.extend(["Elastic Net Classifier", "XGBoost Classifier"])
if unique > 150:
estimators_to_drop.append("CatBoost Classifier")
dropped_estimators = [e for e in estimators if e.name in estimators_to_drop]
if len(dropped_estimators):
self.logger.info(
"Dropping estimators {} because the number of unique targets is {} and `allow_long_running_models` is set to {}".format(
", ".join(sorted([e.name for e in dropped_estimators])),
unique,
self.allow_long_running_models,
)
)
estimators = [e for e in estimators if e not in dropped_estimators]
return estimators
def _create_pipelines(self):
indices = []
pipelines_to_sort = []
pipelines_end = []
self.allowed_pipelines = []
if self.allowed_component_graphs is None:
self.logger.info("Generating pipelines to search over...")
allowed_estimators = get_estimators(
self.problem_type, self.allowed_model_families
)
allowed_estimators = self._filter_estimators(allowed_estimators)
self.logger.debug(
f"allowed_estimators set to {[estimator.name for estimator in allowed_estimators]}"
)
with warnings.catch_warnings(record=True) as w:
warnings.filterwarnings("always", category=ParameterNotUsedWarning)
self.allowed_pipelines = [
make_pipeline(
self.X,
self.y,
estimator,
self.problem_type,
parameters=self._pipeline_params,
sampler_name=self.sampler_name,
)
for estimator in allowed_estimators
]
self._catch_warnings(w)
else:
with warnings.catch_warnings(record=True) as w:
warnings.filterwarnings("always", category=ParameterNotUsedWarning)
self.allowed_pipelines = get_pipelines_from_component_graphs(
self.allowed_component_graphs,
self.problem_type,
self._pipeline_params,
self.random_seed,
)
self._catch_warnings(w)
if self.allowed_pipelines == []:
raise ValueError("No allowed pipelines to search")
if self.ensembling and len(self.allowed_pipelines) == 1:
self.logger.warning(
"Ensembling is set to True, but the number of unique pipelines is one, so ensembling will not run."
)
self.ensembling = False
if self.ensembling and self.max_iterations is not None:
# Baseline + first batch + each pipeline iteration + 1
first_ensembling_iteration = (
1
+ len(self.allowed_pipelines)
+ len(self.allowed_pipelines) * self.pipelines_per_batch
+ 1
)
if self.max_iterations < first_ensembling_iteration:
self.ensembling = False
self.logger.warning(
f"Ensembling is set to True, but max_iterations is too small, so ensembling will not run. Set max_iterations >= {first_ensembling_iteration} to run ensembling."
)
else:
self.logger.info(
f"Ensembling will run at the {first_ensembling_iteration} iteration and every {len(self.allowed_pipelines) * self.pipelines_per_batch} iterations after that."
)
if self.max_batches and self.max_iterations is None:
self.show_batch_output = True
if self.ensembling:
ensemble_nth_batch = len(self.allowed_pipelines) + 1
num_ensemble_batches = (self.max_batches - 1) // ensemble_nth_batch
if num_ensemble_batches == 0:
self.ensembling = False
self.logger.warning(
f"Ensembling is set to True, but max_batches is too small, so ensembling will not run. Set max_batches >= {ensemble_nth_batch + 1} to run ensembling."
)
else:
self.logger.info(
f"Ensembling will run every {ensemble_nth_batch} batches."
)
self.max_iterations = (
1
+ len(self.allowed_pipelines)
+ self.pipelines_per_batch
* (self.max_batches - 1 - num_ensemble_batches)
+ num_ensemble_batches
)
else:
self.max_iterations = (
1
+ len(self.allowed_pipelines)
+ (self.pipelines_per_batch * (self.max_batches - 1))
)
for pipeline in self.allowed_pipelines or []:
if pipeline.model_family in self._estimator_family_order:
indices.append(
self._estimator_family_order.index(pipeline.model_family)
)
pipelines_to_sort.append(pipeline)
else:
pipelines_end.append(pipeline)
pipelines_start = [
pipeline
for _, pipeline in (
sorted(zip(indices, pipelines_to_sort), key=lambda pair: pair[0]) or []
)
]
self.allowed_pipelines = pipelines_start + pipelines_end
self.logger.debug(
f"allowed_pipelines set to {[pipeline.name for pipeline in self.allowed_pipelines]}"
)
self.logger.debug(
f"allowed_model_families set to {self.allowed_model_families}"
)
self.logger.info(f"{len(self.allowed_pipelines)} pipelines ready for search.")
[docs] def next_batch(self):
"""Get the next batch of pipelines to evaluate.
Returns:
list[PipelineBase]: A list of instances of PipelineBase subclasses, ready to be trained and evaluated.
Raises:
AutoMLAlgorithmException: If no results were reported from the first batch.
"""
if self._batch_number == 1:
if len(self._first_batch_results) == 0:
raise AutoMLAlgorithmException(
"No results were reported from the first batch"
)
self._first_batch_results = sorted(
self._first_batch_results, key=itemgetter(0)
)
next_batch = []
if self._batch_number == 0:
next_batch = [
pipeline.new(
parameters=self._transform_parameters(pipeline, {}),
random_seed=self.random_seed,
)
for pipeline in self.allowed_pipelines
]
# One after training all pipelines one round
elif (
self.ensembling
and self._batch_number != 1
and (self._batch_number) % (len(self._first_batch_results) + 1) == 0
):
next_batch = self._create_ensemble()
else:
num_pipelines = (
(len(self._first_batch_results) + 1)
if self.ensembling
else len(self._first_batch_results)
)
idx = (self._batch_number - 1) % num_pipelines
pipeline = self._first_batch_results[idx][1]
for i in range(self.pipelines_per_batch):
proposed_parameters = self._tuners[pipeline.name].propose()
parameters = self._transform_parameters(pipeline, proposed_parameters)
next_batch.append(
pipeline.new(parameters=parameters, random_seed=self.random_seed)
)
self._pipeline_number += len(next_batch)
self._batch_number += 1
return next_batch
[docs] def add_result(self, score_to_minimize, pipeline, trained_pipeline_results):
"""Register results from evaluating a pipeline.
Args:
score_to_minimize (float): The score obtained by this pipeline on the primary objective, converted so that lower values indicate better pipelines.
pipeline (PipelineBase): The trained pipeline object which was used to compute the score.
trained_pipeline_results (dict): Results from training a pipeline.
Raises:
ValueError: If default parameters are not in the acceptable hyperparameter ranges.
"""
if pipeline.model_family != ModelFamily.ENSEMBLE:
if self.batch_number == 1:
try:
super().add_result(
score_to_minimize, pipeline, trained_pipeline_results
)
except ValueError as e:
if "is not within the bounds of the space" in str(e):
raise ValueError(
"Default parameters for components in pipeline {} not in the hyperparameter ranges: {}".format(
pipeline.name, e
)
)
else:
raise (e)
else:
super().add_result(
score_to_minimize, pipeline, trained_pipeline_results
)
if self.batch_number == 1:
self._first_batch_results.append((score_to_minimize, pipeline))
current_best_score = self._best_pipeline_info.get(
pipeline.model_family, {}
).get("mean_cv_score", np.inf)
if (
score_to_minimize is not None
and score_to_minimize < current_best_score
and pipeline.model_family != ModelFamily.ENSEMBLE
):
self._best_pipeline_info.update(
{
pipeline.model_family: {
"mean_cv_score": score_to_minimize,
"pipeline": pipeline,
"parameters": pipeline.parameters,
"id": trained_pipeline_results["id"],
}
}
)
def _transform_parameters(self, pipeline, proposed_parameters):
"""Given a pipeline parameters dict, make sure n_jobs and number_features are set."""
parameters = {}
if "pipeline" in self._pipeline_params:
parameters["pipeline"] = self._pipeline_params["pipeline"]
for (
name,
component_instance,
) in pipeline.component_graph.component_instances.items():
component_class = type(component_instance)
component_parameters = proposed_parameters.get(name, {})
init_params = inspect.signature(component_class.__init__).parameters
# For first batch, pass the pipeline params to the components that need them
if name in self._custom_hyperparameters and self._batch_number == 0:
for param_name, value in self._custom_hyperparameters[name].items():
if isinstance(value, (Integer, Real)):
# get a random value in the space
component_parameters[param_name] = value.rvs(
random_state=self.random_seed
)[0]
# Categorical
else:
component_parameters[param_name] = value.rvs(
random_state=self.random_seed
)
if name in self._pipeline_params and self._batch_number == 0:
for param_name, value in self._pipeline_params[name].items():
component_parameters[param_name] = value
# Inspects each component and adds the following parameters when needed
if "n_jobs" in init_params:
component_parameters["n_jobs"] = self.n_jobs
if "number_features" in init_params:
component_parameters["number_features"] = self.number_features
if (
name in self._pipeline_params
and name == "Drop Columns Transformer"
and self._batch_number > 0
):
component_parameters["columns"] = self._pipeline_params[name]["columns"]
if "pipeline" in self._pipeline_params:
for param_name, value in self._pipeline_params["pipeline"].items():
if param_name in init_params:
component_parameters[param_name] = value
parameters[name] = component_parameters
return parameters
def _catch_warnings(self, warning_list):
parameter_not_used_warnings = []
raised_messages = []
for msg in warning_list:
if isinstance(msg.message, ParameterNotUsedWarning):
parameter_not_used_warnings.append(msg.message)
# Raise non-PNU warnings immediately, but only once per warning
elif str(msg.message) not in raised_messages:
warnings.warn(msg.message)
raised_messages.append(str(msg.message))
# Raise PNU warnings, iff the warning was raised in every pipeline
if len(parameter_not_used_warnings) == len(self.allowed_pipelines) and len(
parameter_not_used_warnings
):
final_message = set([])
for msg in parameter_not_used_warnings:
if len(final_message) == 0:
final_message = final_message.union(msg.components)
else:
final_message = final_message.intersection(msg.components)
warnings.warn(ParameterNotUsedWarning(final_message))