[SPARK-2293] Replace RDD.zip usage by map with predict inside.

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 1.1.0
• Component/s: MLlib
• Target Version/s: 1.1.0
• Assignee: Unassigned
• Reporter: Xiangrui Meng
• Created: 26/Jun/14 17:33
• Updated: 30/Jun/14 23:04
• Resolved: 30/Jun/14 23:04

Description

In our guide, we use

val prediction = model.predict(test.map(_.features))
val predictionAndLabel = prediction.zip(test.map(_.label))

This is not efficient because test will be computed twice. We should change it to

val predictionAndLabel = test.map(p => (model.predict(p.features), p.label))

It is also nice to add a `predictWith` method to predictive models.

def predictWith[V](RDD[(Vector, V)]): RDD[(Double, V)]

But I'm not sure whether this is a good name. `predictWithValue`?