[MINOR] [DOC] fix mllib pydoc warnings

Switch to correct Sphinx syntax. MechCoder

Author: Xiangrui Meng <meng@databricks.com>

Closes #8169 from mengxr/mllib-pydoc-fix.

python/pyspark/mllib/regression.py

@@ -207,8 +207,10 @@ class LinearRegressionWithSGD(object):
         Train a linear regression model using Stochastic Gradient
         Descent (SGD).
         This solves the least squares regression formulation
-                f(weights) = 1/n ||A weights-y||^2^
-        (which is the mean squared error).
+
+            f(weights) = 1/(2n) ||A weights - y||^2,
+
+        which is the mean squared error.
         Here the data matrix has n rows, and the input RDD holds the
         set of rows of A, each with its corresponding right hand side
         label y. See also the documentation for the precise formulation.
@@ -334,7 +336,9 @@ class LassoWithSGD(object):
         Stochastic Gradient Descent.
         This solves the l1-regularized least squares regression
         formulation
-            f(weights) = 1/2n ||A weights-y||^2^  + regParam ||weights||_1
+
+            f(weights) = 1/(2n) ||A weights - y||^2  + regParam ||weights||_1.
+
         Here the data matrix has n rows, and the input RDD holds the
         set of rows of A, each with its corresponding right hand side
         label y. See also the documentation for the precise formulation.
@@ -451,7 +455,9 @@ class RidgeRegressionWithSGD(object):
         Stochastic Gradient Descent.
         This solves the l2-regularized least squares regression
         formulation
-            f(weights) = 1/2n ||A weights-y||^2^  + regParam/2 ||weights||^2^
+
+            f(weights) = 1/(2n) ||A weights - y||^2 + regParam/2 ||weights||^2.
+
         Here the data matrix has n rows, and the input RDD holds the
         set of rows of A, each with its corresponding right hand side
         label y. See also the documentation for the precise formulation.

python/pyspark/mllib/util.py

@@ -300,6 +300,7 @@ class LinearDataGenerator(object):
         :param: seed      Random Seed
         :param: eps       Used to scale the noise. If eps is set high,
                           the amount of gaussian noise added is more.
+
         Returns a list of LabeledPoints of length nPoints
         """
         weights = [float(weight) for weight in weights]