[SPARK-8784] [SQL] Add Python API for hex and unhex

Also improve the performance of hex/unhex

Author: Davies Liu <davies@databricks.com>

Closes #7181 from davies/hex and squashes the following commits:

f032fbb [Davies Liu] Merge branch 'hex' of github.com:davies/spark into hex
49e325f [Davies Liu] Merge branch 'master' of github.com:apache/spark into hex
b31fc9a [Davies Liu] Update math.scala
25156b7 [Davies Liu] address comments and fix test
c3af78c [Davies Liu] address commments
1a24082 [Davies Liu] Add Python API for hex and unhex

1 files changed, 28 insertions, 0 deletions

diff --git a/python/pyspark/sql/functions.py b/python/pyspark/sql/functions.py
index 12263e6a75..8a470ce19b 100644
--- a/python/pyspark/sql/functions.py
+++ b/python/pyspark/sql/functions.py
@@ -383,6 +383,34 @@ def randn(seed=None):
 
 @ignore_unicode_prefix
 @since(1.5)
+def hex(col):
+    """Computes hex value of the given column, which could be StringType,
+    BinaryType, IntegerType or LongType.
+
+    >>> sqlContext.createDataFrame([('ABC', 3)], ['a', 'b']).select(hex('a'), hex('b')).collect()
+    [Row(hex(a)=u'414243', hex(b)=u'3')]
+    """
+    sc = SparkContext._active_spark_context
+    jc = sc._jvm.functions.hex(_to_java_column(col))
+    return Column(jc)
+
+
+@ignore_unicode_prefix
+@since(1.5)
+def unhex(col):
+    """Inverse of hex. Interprets each pair of characters as a hexadecimal number
+    and converts to the byte representation of number.
+
+    >>> sqlContext.createDataFrame([('414243',)], ['a']).select(unhex('a')).collect()
+    [Row(unhex(a)=bytearray(b'ABC'))]
+    """
+    sc = SparkContext._active_spark_context
+    jc = sc._jvm.functions.unhex(_to_java_column(col))
+    return Column(jc)
+
+
+@ignore_unicode_prefix
+@since(1.5)
 def sha1(col):
     """Returns the hex string result of SHA-1.