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我在这里通过 JohnSnowLabs SpellChecker 。

我在那里找到了Norvig的算法实现，示例部分只有以下两行：

import com.johnsnowlabs.nlp.annotator.NorvigSweetingModel
NorvigSweetingModel.pretrained()

如何在df下面的数据框 ( ) 上应用此预训练模型以更正“”列的拼写names？

+----------------+---+------------+
|           names|age|       color|
+----------------+---+------------+
|      [abc, cde]| 19|    red, abc|
|[eefg, efa, efb]|192|efg, efz efz|
+----------------+---+------------+

我试图这样做：

val schk = NorvigSweetingModel.pretrained().setInputCols("names").setOutputCol("Corrected")

val cdf = schk.transform(df)

但是上面的代码给了我以下错误：

java.lang.IllegalArgumentException: requirement failed: Wrong or missing inputCols annotators in SPELL_a1f11bacb851. Received inputCols: names. Make sure such columns have following annotator types: token
  at scala.Predef$.require(Predef.scala:224)
  at com.johnsnowlabs.nlp.AnnotatorModel.transform(AnnotatorModel.scala:51)
  ... 49 elided
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1 回答 1

5

spark-nlp被设计用于其自己的特定管道和不同转换器的输入列必须包含特殊的元数据。

异常已经告诉您NorvigSweetingModel应该对 的输入进行标记：

确保此类列具有以下注释器类型：token

如果我没记错的话，至少你会在这里组装文档并标记化。

import com.johnsnowlabs.nlp.DocumentAssembler
import com.johnsnowlabs.nlp.annotator.NorvigSweetingModel
import com.johnsnowlabs.nlp.annotators.Tokenizer
import org.apache.spark.ml.Pipeline

val df = Seq(Seq("abc", "cde"), Seq("eefg", "efa", "efb")).toDF("names")

val nlpPipeline = new Pipeline().setStages(Array(
  new DocumentAssembler().setInputCol("names").setOutputCol("document"),
  new Tokenizer().setInputCols("document").setOutputCol("tokens"),
  NorvigSweetingModel.pretrained().setInputCols("tokens").setOutputCol("corrected")
))

像Pipeline这样，可以通过小的调整应用于您的数据 - 输入数据必须string不是array<string>*：

val result = df
  .transform(_.withColumn("names", concat_ws(" ", $"names")))
  .transform(df => nlpPipeline.fit(df).transform(df))
result.show()

+------------+--------------------+--------------------+--------------------+
|       names|            document|              tokens|           corrected|
+------------+--------------------+--------------------+--------------------+
|     abc cde|[[document, 0, 6,...|[[token, 0, 2, ab...|[[token, 0, 2, ab...|
|eefg efa efb|[[document, 0, 11...|[[token, 0, 3, ee...|[[token, 0, 3, ee...|
+------------+--------------------+--------------------+--------------------+

如果你想要一个可以导出的输出，你应该扩展你的Pipelinewith Finisher。

import com.johnsnowlabs.nlp.Finisher

new Finisher().setInputCols("corrected").transform(result).show

 +------------+------------------+
 |       names|finished_corrected|
 +------------+------------------+
 |     abc cde|        [abc, cde]|
 |eefg efa efb|  [eefg, efa, efb]|
 +------------+------------------+

* 根据文档 DocumentAssembler

可以读取 String 列或 Array[String]

但它在 1.7.3 中看起来并不适用：

df.transform(df => nlpPipeline.fit(df).transform(df)).show()

org.apache.spark.sql.AnalysisException: cannot resolve 'UDF(names)' due to data type mismatch: argument 1 requires string type, however, '`names`' is of array<string> type.;;
'Project [names#62, UDF(names#62) AS document#343]
+- AnalysisBarrier
      +- Project [value#60 AS names#62]
         +- LocalRelation [value#60]
于 2018-11-21T19:04:57.437 回答