How to implement zipWithIndex as a UDF?

[Benyi Wang]

If I have two columns

StructType(Seq(
  StructField("id", LongType),
  StructField("phones", ArrayType(StringType))))

I want to add index for “phones” before I explode it.

Can this be implemented as GenericUDF?

I tried DataFrame.explode. It worked for simple types like string, but I
could not figure out how to handle a nested type like StructType.

Can somebody shed a light?

I’m using spark 1.5.1.
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