[SPARK-11723][ML][DOC] Use LibSVM data source rather than MLUtils.loadLibSVMFile to load DataFrame

Use LibSVM data source rather than MLUtils.loadLibSVMFile to load DataFrame, include:
* Use libSVM data source for all example codes under examples/ml, and remove unused import.
* Use libSVM data source for user guides under ml-*** which were omitted by #8697.
* Fix bug: We should use ```sqlContext.read().format("libsvm").load(path)``` at Java side, but the API doc and user guides misuse as ```sqlContext.read.format("libsvm").load(path)```.
* Code cleanup.

mengxr

Author: Yanbo Liang <ybliang8@gmail.com>

Closes #9690 from yanboliang/spark-11723.

1 files changed, 2 insertions, 3 deletions

diff --git a/examples/src/main/python/ml/decision_tree_regression_example.py b/examples/src/main/python/ml/decision_tree_regression_example.py
index 3857aed538..439e398947 100644
--- a/examples/src/main/python/ml/decision_tree_regression_example.py
+++ b/examples/src/main/python/ml/decision_tree_regression_example.py
@@ -28,7 +28,6 @@ from pyspark.ml import Pipeline
 from pyspark.ml.regression import DecisionTreeRegressor
 from pyspark.ml.feature import VectorIndexer
 from pyspark.ml.evaluation import RegressionEvaluator
-from pyspark.mllib.util import MLUtils
 # $example off$
 
 if __name__ == "__main__":
@@ -36,8 +35,8 @@ if __name__ == "__main__":
     sqlContext = SQLContext(sc)
 
     # $example on$
-    # Load and parse the data file, converting it to a DataFrame.
-    data = MLUtils.loadLibSVMFile(sc, "data/mllib/sample_libsvm_data.txt").toDF()
+    # Load the data stored in LIBSVM format as a DataFrame.
+    data = sqlContext.read.format("libsvm").load("data/mllib/sample_libsvm_data.txt")
 
     # Automatically identify categorical features, and index them.
     # We specify maxCategories so features with > 4 distinct values are treated as continuous.