如何封装不同 的分箱 （Binning）算法为一个spark Estimator？

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接上文：spark 特征工程 – 分箱 Binning（如何实现等频、等宽分箱）

简介 – 什么是 spark Estimator

官方文档有一篇有点年代了：

https://spark.apache.org/docs/latest/ml-pipeline.html

先来看看以下几个核心概念：

PipeLine：工作流。

A simple pipeline, which acts as an estimator. A Pipeline consists of a sequence of stages, each of which is either an Estimator or a Transformer. When Pipeline.fit is called, the stages are executed in order. If a stage is an Estimator, its Estimator.fit method will be called on the input dataset to fit a model. Then the model, which is a transformer, will be used to transform the dataset as the input to the nex