Are you looking for UDFs?

https://jaceklaskowski.gitbooks.io/mastering-apache-spark/content/spark-sql-udfs.html

On Sun, Nov 20, 2016 at 3:12 AM Stuart White <stuart.whi...@gmail.com>
wrote:

> I'd like to allow for runtime-configured Column expressions in my
> Spark SQL application.  For example, if my application needs a 5-digit
> zip code, but the file I'm processing contains a 9-digit zip code, I'd
> like to be able to configure my application with the expression
> "substring('zipCode, 0, 5)" to use for the zip code.
>
> So, I think I'm looking for something like this:
>
> def parseColumnExpression(colExpr: String) : Column
>
> I see that SparkSession's sql() method exists to take a string and
> parse it into a DataFrame.  But that's not quite what I want.
>
> Does a mechanism exist that would allow me to take a string
> representation of a column expression and parse it into an actual
> column expression (something that could be use in a .select() call,
> for example)?
>
> Thanks!
>
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