3 files changed, 26 insertions, 2 deletions
diff --git a/mllib/src/main/scala/org/apache/spark/ml/feature/RFormula.scala b/mllib/src/main/scala/org/apache/spark/ml/feature/RFormula.scala
index 2916b6d9df..a7ca0fe252 100644
--- a/mllib/src/main/scala/org/apache/spark/ml/feature/RFormula.scala
+++ b/mllib/src/main/scala/org/apache/spark/ml/feature/RFormula.scala
@@ -182,7 +182,7 @@ class RFormula(override val uid: String)
 
   override def copy(extra: ParamMap): RFormula = defaultCopy(extra)
 
-  override def toString: String = s"RFormula(${get(formula)}) (uid=$uid)"
+  override def toString: String = s"RFormula(${get(formula).getOrElse("")}) (uid=$uid)"
 }
 
 @Since("2.0.0")
diff --git a/mllib/src/main/scala/org/apache/spark/ml/feature/RFormulaParser.scala b/mllib/src/main/scala/org/apache/spark/ml/feature/RFormulaParser.scala
index 19aecff038..2dd565a782 100644
--- a/mllib/src/main/scala/org/apache/spark/ml/feature/RFormulaParser.scala
+++ b/mllib/src/main/scala/org/apache/spark/ml/feature/RFormulaParser.scala
@@ -126,7 +126,19 @@ private[ml] case class ParsedRFormula(label: ColumnRef, terms: Seq[Term]) {
  * @param hasIntercept whether the formula specifies fitting with an intercept.
  */
 private[ml] case class ResolvedRFormula(
-  label: String, terms: Seq[Seq[String]], hasIntercept: Boolean)
+  label: String, terms: Seq[Seq[String]], hasIntercept: Boolean) {
+
+  override def toString: String = {
+    val ts = terms.map {
+      case t if t.length > 1 =>
+        s"${t.mkString("{", ",", "}")}"
+      case t =>
+        t.mkString
+    }
+    val termStr = ts.mkString("[", ",", "]")
+    s"ResolvedRFormula(label=$label, terms=$termStr, hasIntercept=$hasIntercept)"
+  }
+}
 
 /**
  * R formula terms. See the R formula docs here for more information:
diff --git a/python/pyspark/ml/feature.py b/python/pyspark/ml/feature.py
index bfb2fb7071..ca77ac395d 100755
--- a/python/pyspark/ml/feature.py
+++ b/python/pyspark/ml/feature.py
@@ -2528,6 +2528,8 @@ class RFormula(JavaEstimator, HasFeaturesCol, HasLabelCol, JavaMLReadable, JavaM
     True
     >>> loadedRF.getLabelCol() == rf.getLabelCol()
     True
+    >>> str(loadedRF)
+    'RFormula(y ~ x + s) (uid=...)'
     >>> modelPath = temp_path + "/rFormulaModel"
     >>> model.save(modelPath)
     >>> loadedModel = RFormulaModel.load(modelPath)
@@ -2542,6 +2544,8 @@ class RFormula(JavaEstimator, HasFeaturesCol, HasLabelCol, JavaMLReadable, JavaM
     |0.0|0.0|  a|[0.0,1.0]|  0.0|
     +---+---+---+---------+-----+
     ...
+    >>> str(loadedModel)
+    'RFormulaModel(ResolvedRFormula(label=y, terms=[x,s], hasIntercept=true)) (uid=...)'
 
     .. versionadded:: 1.5.0
     """
@@ -2586,6 +2590,10 @@ class RFormula(JavaEstimator, HasFeaturesCol, HasLabelCol, JavaMLReadable, JavaM
     def _create_model(self, java_model):
         return RFormulaModel(java_model)
 
+    def __str__(self):
+        formulaStr = self.getFormula() if self.isDefined(self.formula) else ""
+        return "RFormula(%s) (uid=%s)" % (formulaStr, self.uid)
+
 
 class RFormulaModel(JavaModel, JavaMLReadable, JavaMLWritable):
     """
@@ -2597,6 +2605,10 @@ class RFormulaModel(JavaModel, JavaMLReadable, JavaMLWritable):
     .. versionadded:: 1.5.0
     """
 
+    def __str__(self):
+        resolvedFormula = self._call_java("resolvedFormula")
+        return "RFormulaModel(%s) (uid=%s)" % (resolvedFormula, self.uid)
+
 
 @inherit_doc
 class ChiSqSelector(JavaEstimator, HasFeaturesCol, HasOutputCol, HasLabelCol, JavaMLReadable,