From 2388de51912efccaceeb663ac56fc500a79d2ceb Mon Sep 17 00:00:00 2001
From: Feynman Liang <feynman.liang@gmail.com>
Date: Tue, 19 Jan 2016 11:08:52 -0800
Subject: [SPARK-12804][ML] Fix LogisticRegression with FitIntercept on all
 same label training data

CC jkbradley mengxr dbtsai

Author: Feynman Liang <feynman.liang@gmail.com>

Closes #10743 from feynmanliang/SPARK-12804.
---
 .../classification/LogisticRegressionSuite.scala   | 43 ++++++++++++++++++++++
 1 file changed, 43 insertions(+)

(limited to 'mllib/src/test')

diff --git a/mllib/src/test/scala/org/apache/spark/ml/classification/LogisticRegressionSuite.scala b/mllib/src/test/scala/org/apache/spark/ml/classification/LogisticRegressionSuite.scala
index ff0d0ff771..972c0868a4 100644
--- a/mllib/src/test/scala/org/apache/spark/ml/classification/LogisticRegressionSuite.scala
+++ b/mllib/src/test/scala/org/apache/spark/ml/classification/LogisticRegressionSuite.scala
@@ -30,6 +30,7 @@ import org.apache.spark.mllib.regression.LabeledPoint
 import org.apache.spark.mllib.util.MLlibTestSparkContext
 import org.apache.spark.mllib.util.TestingUtils._
 import org.apache.spark.sql.{DataFrame, Row}
+import org.apache.spark.sql.functions.lit
 
 class LogisticRegressionSuite
   extends SparkFunSuite with MLlibTestSparkContext with DefaultReadWriteTest {
@@ -883,6 +884,48 @@ class LogisticRegressionSuite
     assert(model1a0.intercept ~== model1b.intercept absTol 1E-3)
   }
 
+  test("logistic regression with all labels the same") {
+    val sameLabels = dataset
+      .withColumn("zeroLabel", lit(0.0))
+      .withColumn("oneLabel", lit(1.0))
+
+    // fitIntercept=true
+    val lrIntercept = new LogisticRegression()
+      .setFitIntercept(true)
+      .setMaxIter(3)
+
+    val allZeroInterceptModel = lrIntercept
+      .setLabelCol("zeroLabel")
+      .fit(sameLabels)
+    assert(allZeroInterceptModel.coefficients ~== Vectors.dense(0.0) absTol 1E-3)
+    assert(allZeroInterceptModel.intercept === Double.NegativeInfinity)
+    assert(allZeroInterceptModel.summary.totalIterations === 0)
+
+    val allOneInterceptModel = lrIntercept
+      .setLabelCol("oneLabel")
+      .fit(sameLabels)
+    assert(allOneInterceptModel.coefficients ~== Vectors.dense(0.0) absTol 1E-3)
+    assert(allOneInterceptModel.intercept === Double.PositiveInfinity)
+    assert(allOneInterceptModel.summary.totalIterations === 0)
+
+    // fitIntercept=false
+    val lrNoIntercept = new LogisticRegression()
+      .setFitIntercept(false)
+      .setMaxIter(3)
+
+    val allZeroNoInterceptModel = lrNoIntercept
+      .setLabelCol("zeroLabel")
+      .fit(sameLabels)
+    assert(allZeroNoInterceptModel.intercept === 0.0)
+    assert(allZeroNoInterceptModel.summary.totalIterations > 0)
+
+    val allOneNoInterceptModel = lrNoIntercept
+      .setLabelCol("oneLabel")
+      .fit(sameLabels)
+    assert(allOneNoInterceptModel.intercept === 0.0)
+    assert(allOneNoInterceptModel.summary.totalIterations > 0)
+  }
+
   test("read/write") {
     def checkModelData(model: LogisticRegressionModel, model2: LogisticRegressionModel): Unit = {
       assert(model.intercept === model2.intercept)
-- 
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