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python - Hyperopt 与 Spark MlLib 的集成

问题描述

有没有人有一个将 Hyperopt 集成到 Spark 的 MlLib 中的好例子？我一直在尝试在 Databricks 上这样做并继续遇到同样的错误。我不确定这是否是我的目标函数的问题，或者是否与 pyspark 上的 Spark ML 以及它如何与 Databricks 挂钩。

import itertools
from pyspark.sql import functions as f
from pyspark.sql import DataFrame
from pyspark.sql.types import *

from pyspark.ml import Pipeline, PipelineModel
from pyspark.ml.feature import OneHotEncoder, Imputer, VectorAssembler, StringIndexer
from pyspark.ml.classification import RandomForestClassifier, LogisticRegression, GBTClassifier
from pyspark.ml.classification import GBTClassificationModel
from pyspark.ml.evaluation import BinaryClassificationEvaluator
from pyspark.ml.tuning import CrossValidator, ParamGridBuilder, CrossValidatorModel
from sklearn.metrics import classification_report, confusion_matrix, roc_auc_score
import numpy as np
from itertools import product
from hyperopt import fmin, hp, tpe, STATUS_OK, SparkTrials
import pandas as pd
from matplotlib import pyplot as plt
from sklearn.model_selection import train_test_split

search_space ={'maxDepth'   : hp.choice("maxDepth", np.arange(3, 8, dtype=int)),
        'maxIter'       : hp.uniform("maxIter", 200,800),
        'featureSubsetStrategy' : str(hp.quniform("featureSubsetStrategy", .5,1,.1)),
        'minInstancesPerNode' : hp.uniform("min_child_weight", 1,10),
        'stepSize'    : hp.loguniform('stepSize', np.log(0.01), np.log(0.1)),
        'subsamplingRate'    : hp.quniform("featureSubsetStrategy", .5,1,.1)   
    }
evaluator = BinaryClassificationEvaluator(labelCol="positive")

def train(params):
  gbtModel = GBTClassifier(labelCol="positive", featuresCol="features").fit(train)
  predictions_val = gbtModel.predict(val.map(lambda x: x.features))
  labelsAndPredictions = val.map(lambda lp: lp.label).zip(predictions_val)
  ROC = evaluator.evaluate(predictions_val, {evaluator.metricName: "areaUnderROC"})

  return {'ROC': ROC, 'status': STATUS_OK}



N_HYPEROPT_PROBES = 1000 #can increase, keep small for testing
EARLY_STOPPING = 50
HYPEROPT_ALGO = tpe.suggest
NB_CV_FOLDS = 5 # for testing, can increase

obj_call_count = 0
cur_best_score = 1000000
spark_trials = SparkTrials(parallelism=4)
best = fmin(fn=train,
             space=search_space,
              algo=HYPEROPT_ALGO,
                     max_evals=N_HYPEROPT_PROBES,
                     trials=spark_trials,
                     verbose=1)

运行后，我收到以下错误：

Total Trials: 0: 0 succeeded, 0 failed, 0 cancelled. py4j.Py4JException: Method __getstate__([]) does not exist

标签： pythonpysparkhyperopt

解决方案

不确定这是否为时已晚，但 SparkTrials 仅适用于单机 ML 模型，例如 scikit-learn 库中的模型。对于 Spark MLib，您应该使用 Trials（您不需要将 trial 参数传递给 fmin 函数）

您可以在此处找到更多详细信息：http: //hyperopt.github.io/hyperopt/scaleout/spark/

由于 SparkTrials 在一个 Spark 工作人员上拟合和评估每个模型，因此它仅限于调整单机 ML 模型和工作流，例如 scikit-learn 或单机 TensorFlow。对于 Apache Spark MLlib 或 Horovod 等分布式 ML 算法，您可以使用 Hyperopt 的默认 Trials 类。

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