Github user dbtsai commented on a diff in the pull request:

    https://github.com/apache/spark/pull/10788#discussion_r50931610
  
    --- Diff: 
mllib/src/main/scala/org/apache/spark/ml/classification/LogisticRegression.scala
 ---
    @@ -343,22 +355,36 @@ class LogisticRegression @Since("1.2.0") (
             val initialCoefficientsWithIntercept =
               Vectors.zeros(if ($(fitIntercept)) numFeatures + 1 else 
numFeatures)
     
    -        if ($(fitIntercept)) {
    +        if (optInitialModel.isDefined && 
optInitialModel.get.coefficients.size != numFeatures) {
    +          val vec = optInitialModel.get.coefficients
    +          logWarning(
    +            s"Initial coefficients provided ${vec} did not match the 
expected size ${numFeatures}")
    +        }
    +
    +        if (optInitialModel.isDefined && 
optInitialModel.get.coefficients.size == numFeatures) {
    +          val initialCoefficientsWithInterceptArray = 
initialCoefficientsWithIntercept.toArray
    +          optInitialModel.get.coefficients.foreachActive { case (index, 
value) =>
    +            initialCoefficientsWithInterceptArray(index) = value
    +          }
    +          if ($(fitIntercept)) {
    +            initialCoefficientsWithInterceptArray(numFeatures) == 
optInitialModel.get.intercept
    +          }
    +        } else if ($(fitIntercept)) {
               /*
                  For binary logistic regression, when we initialize the 
coefficients as zeros,
                  it will converge faster if we initialize the intercept such 
that
                  it follows the distribution of the labels.
     
                  {{{
    -               P(0) = 1 / (1 + \exp(b)), and
    -               P(1) = \exp(b) / (1 + \exp(b))
    +             P(0) = 1 / (1 + \exp(b)), and
    +             P(1) = \exp(b) / (1 + \exp(b))
                  }}}, hence
                  {{{
    -               b = \log{P(1) / P(0)} = \log{count_1 / count_0}
    +             b = \log{P(1) / P(0)} = \log{count_1 / count_0}
    --- End diff --
    
    put two spaces back.


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