prefix span output formatting

问题:

I am trying to run following example code:

import org.apache.spark.mllib.fpm.PrefixSpan

val sequences = sc.parallelize(Seq(
 Array(Array(1, 2), Array(3)),
 Array(Array(1), Array(3, 2), Array(1, 2)),
 Array(Array(1, 2), Array(5)),
 Array(Array(6))
), 2).cache()

val prefixSpan = new PrefixSpan()
 .setMinSupport(0.5)
 .setMaxPatternLength(5)

val model = prefixSpan.run(sequences)
model.freqSequences.collect().foreach { freqSequence =>
  println(
    freqSequence.sequence.map(_.mkString("[", ", ", "]")).mkString("[", ", ", "]") +
", " + freqSequence.freq
  )
}

I need to format model.freqSequences to something similar to following(it is a dataframe with sequence and freq)

|[WrappedArray(2,3)] |  3
|[WrappedArray(1)]   |  2
|[WrappedArray(2,1)] |  1

回答1:

Using flatten on freqSequence.sequence and applying toDF should give your desired output

model.freqSequences.map(freqSequence => (freqSequence.sequence.flatten, freqSequence.freq)).toDF("array", "freq").show(false)

which should give you

+------+----+
|array |freq|
+------+----+
|[2]   |3   |
|[3]   |2   |
|[1]   |3   |
|[2, 1]|3   |
|[1, 3]|2   |
+------+----+

I hope the answer is helpful