[MINOR] Fix Typos 'an -> a'

## What changes were proposed in this pull request?

`an -> a`

Use cmds like `find . -name '*.R' | xargs -i sh -c "grep -in ' an [^aeiou]' {} && echo {}"` to generate candidates, and review them one by one.

## How was this patch tested?
manual tests

Author: Zheng RuiFeng <ruifengz@foxmail.com>

Closes #13515 from zhengruifeng/an_a.

2 files changed, 2 insertions, 2 deletions

diff --git a/python/pyspark/mllib/classification.py b/python/pyspark/mllib/classification.py
index f186217031..3734f87405 100644
--- a/python/pyspark/mllib/classification.py
+++ b/python/pyspark/mllib/classification.py
@@ -52,7 +52,7 @@ class LinearClassificationModel(LinearModel):
 
         Sets the threshold that separates positive predictions from
         negative predictions. An example with prediction score greater
-        than or equal to this threshold is identified as an positive,
+        than or equal to this threshold is identified as a positive,
         and negative otherwise. It is used for binary classification
         only.
         """
diff --git a/python/pyspark/mllib/common.py b/python/pyspark/mllib/common.py
index 6bc2b1e646..31afdf576b 100644
--- a/python/pyspark/mllib/common.py
+++ b/python/pyspark/mllib/common.py
@@ -60,7 +60,7 @@ _picklable_classes = [
 
 # this will call the MLlib version of pythonToJava()
 def _to_java_object_rdd(rdd):
-    """ Return an JavaRDD of Object by unpickling
+    """ Return a JavaRDD of Object by unpickling
 
     It will convert each Python object into Java object by Pyrolite, whenever the
     RDD is serialized in batch or not.