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https://issues.apache.org/jira/browse/SPARK-19217?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Hyukjin Kwon resolved SPARK-19217.
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Resolution: Later
Let's track this in another JIRA. It's been inactive for so long time. At least
work around is easy and to natively support this in cast, it looks quite big
challenge.
> Offer easy cast from vector to array
> ------------------------------------
>
> Key: SPARK-19217
> URL: https://issues.apache.org/jira/browse/SPARK-19217
> Project: Spark
> Issue Type: Improvement
> Components: ML, PySpark, SQL
> Affects Versions: 2.1.0
> Reporter: Nicholas Chammas
> Priority: Minor
>
> Working with ML often means working with DataFrames with vector columns. You
> can't save these DataFrames to storage (edit: at least as ORC) without
> converting the vector columns to array columns, and there doesn't appear to
> an easy way to make that conversion.
> This is a common enough problem that it is [documented on Stack
> Overflow|http://stackoverflow.com/q/35855382/877069]. The current solutions
> to making the conversion from a vector column to an array column are:
> # Convert the DataFrame to an RDD and back
> # Use a UDF
> Both approaches work fine, but it really seems like you should be able to do
> something like this instead:
> {code}
> (le_data
> .select(
> col('features').cast('array').alias('features')
> ))
> {code}
> We already have an {{ArrayType}} in {{pyspark.sql.types}}, but it appears
> that {{cast()}} doesn't support this conversion.
> Would this be an appropriate thing to add?
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