[SPARK-20097][ML] Fix visibility discrepancy with numInstances and degreesOfFreedom in LR and GLR

## What changes were proposed in this pull request?

- made `numInstances` public in GLR
- made `degreesOfFreedom` public in LR

## How was this patch tested?

reran the concerned test suites

Author: Benjamin Fradet <benjamin.fradet@gmail.com>

Closes #17431 from BenFradet/SPARK-20097.

2 files changed, 4 insertions, 2 deletions

diff --git a/mllib/src/main/scala/org/apache/spark/ml/regression/GeneralizedLinearRegression.scala b/mllib/src/main/scala/org/apache/spark/ml/regression/GeneralizedLinearRegression.scala
index 33137b0c0f..d6093a01c6 100644
--- a/mllib/src/main/scala/org/apache/spark/ml/regression/GeneralizedLinearRegression.scala
+++ b/mllib/src/main/scala/org/apache/spark/ml/regression/GeneralizedLinearRegression.scala
@@ -1133,7 +1133,8 @@ class GeneralizedLinearRegressionSummary private[regression] (
   private[regression] lazy val link: Link = familyLink.link
 
   /** Number of instances in DataFrame predictions. */
-  private[regression] lazy val numInstances: Long = predictions.count()
+  @Since("2.2.0")
+  lazy val numInstances: Long = predictions.count()
 
   /** The numeric rank of the fitted linear model. */
   @Since("2.0.0")
diff --git a/mllib/src/main/scala/org/apache/spark/ml/regression/LinearRegression.scala b/mllib/src/main/scala/org/apache/spark/ml/regression/LinearRegression.scala
index 45df1d9be6..f7e3c8fa5b 100644
--- a/mllib/src/main/scala/org/apache/spark/ml/regression/LinearRegression.scala
+++ b/mllib/src/main/scala/org/apache/spark/ml/regression/LinearRegression.scala
@@ -696,7 +696,8 @@ class LinearRegressionSummary private[regression] (
   lazy val numInstances: Long = predictions.count()
 
   /** Degrees of freedom */
-  private val degreesOfFreedom: Long = if (privateModel.getFitIntercept) {
+  @Since("2.2.0")
+  val degreesOfFreedom: Long = if (privateModel.getFitIntercept) {
     numInstances - privateModel.coefficients.size - 1
   } else {
     numInstances - privateModel.coefficients.size