ensuring RDD indices remain immutable
I have an RDD that serves as a feature look-up table downstream in my analysis. I create it using the zipWithIndex() and because I suppose that the elements of the RDD could end up in a different order if it is regenerated at any point, I cache it to try and ensure that the (feature -- index) mapping remains fixed. However, I'm having trouble verifying that this is actually robust -- can someone comment whether using such a mapping should be stable or is there another preferred method? zipWithUniqueID() isn't optimal since max ID generated this way is always greater than the number of features so I'm trying to avoid it. -- View this message in context: http://apache-spark-user-list.1001560.n3.nabble.com/ensuring-RDD-indices-remain-immutable-tp20094.html Sent from the Apache Spark User List mailing list archive at Nabble.com. - To unsubscribe, e-mail: user-unsubscr...@spark.apache.org For additional commands, e-mail: user-h...@spark.apache.org
Re: ensuring RDD indices remain immutable
I think the robust thing to do is sort the RDD, and then zipWithIndex. Even if the RDD is recomputed, the ordering and thus assignment of IDs should be the same. On Mon, Dec 1, 2014 at 2:36 PM, rok rokros...@gmail.com wrote: I have an RDD that serves as a feature look-up table downstream in my analysis. I create it using the zipWithIndex() and because I suppose that the elements of the RDD could end up in a different order if it is regenerated at any point, I cache it to try and ensure that the (feature -- index) mapping remains fixed. However, I'm having trouble verifying that this is actually robust -- can someone comment whether using such a mapping should be stable or is there another preferred method? zipWithUniqueID() isn't optimal since max ID generated this way is always greater than the number of features so I'm trying to avoid it. -- View this message in context: http://apache-spark-user-list.1001560.n3.nabble.com/ensuring-RDD-indices-remain-immutable-tp20094.html Sent from the Apache Spark User List mailing list archive at Nabble.com. - To unsubscribe, e-mail: user-unsubscr...@spark.apache.org For additional commands, e-mail: user-h...@spark.apache.org - To unsubscribe, e-mail: user-unsubscr...@spark.apache.org For additional commands, e-mail: user-h...@spark.apache.org
Re: ensuring RDD indices remain immutable
true though I was hoping to avoid having to sort... maybe there's no way around it. Thanks! -- View this message in context: http://apache-spark-user-list.1001560.n3.nabble.com/ensuring-RDD-indices-remain-immutable-tp20094p20104.html Sent from the Apache Spark User List mailing list archive at Nabble.com. - To unsubscribe, e-mail: user-unsubscr...@spark.apache.org For additional commands, e-mail: user-h...@spark.apache.org
