diff --git a/python/pyspark/mllib/linalg.py b/python/pyspark/mllib/linalg.py
index e13b814072688..9c3d806afa8fb 100644
--- a/python/pyspark/mllib/linalg.py
+++ b/python/pyspark/mllib/linalg.py
@@ -209,17 +209,26 @@ def __init__(self, ar):
         self.array = ar
 
     @staticmethod
-    def parse(vectorString):
+    def parse(s):
         """
         Parse string representation back into the DenseVector.
 
         >>> DenseVector.parse(' [ 0.0,1.0,2.0,  3.0]')
         DenseVector([0.0, 1.0, 2.0, 3.0])
         """
-        start = vectorString.find('[')
-        end = vectorString.find(']')
-        vectorString = vectorString[start + 1: end]
-        return DenseVector([float(val) for val in vectorString.split(',')])
+        start = s.find('[')
+        if start == -1:
+            raise ValueError("Array should start with '['")
+        end = s.find(']')
+        if end == -1:
+            raise ValueError("Array should end with  ']")
+        s = s[start + 1: end]
+
+        try:
+            values = [float(val) for val in s.split(',')]
+        except ValueError:
+            raise ValueError("Unable to parse values.")
+        return DenseVector(values)
 
     def __reduce__(self):
         return DenseVector, (self.array.tostring(),)
@@ -436,28 +445,51 @@ def __reduce__(self):
             (self.size, self.indices.tostring(), self.values.tostring()))
 
     @staticmethod
-    def parse(vectorString):
+    def parse(s):
         """
         Parse string representation back into the DenseVector.
 
         >>> SparseVector.parse(' (4, [0,1 ],[ 4.0,5.0] )')
         SparseVector(4, {0: 4.0, 1: 5.0})
         """
-        start = vectorString.find('(')
-        end = vectorString.find(')')
-        vectorString = vectorString[start+1: end].strip()
-        size = int(vectorString[0])
-
-        ind_start = vectorString.find('[')
-        ind_end = vectorString.find(']')
-        ind_list = vectorString[ind_start + 1: ind_end].split(',')
-        indices = [int(ind) for ind in ind_list]
-        vectorString = vectorString[ind_end + 1:].strip()
-
-        val_start = vectorString.find('[')
-        val_end = vectorString.find(']')
-        val_list = vectorString[val_start + 1: val_end].split(',')
-        values = [float(val) for val in val_list]
+        start = s.find('(')
+        if start == -1:
+            raise ValueError("Tuple should start with '('")
+        end = s.find(')')
+        if start == -1:
+            raise ValueError("Tuple should end with ')'")
+        s = s[start + 1: end].strip()
+
+        size = s[: s.find(',')]
+        try:
+            size = int(size)
+        except ValueError:
+            raise ValueError("Cannot parse size %s." % size)
+
+        ind_start = s.find('[')
+        if ind_start == -1:
+            raise ValueError("Indices array should start with '('.")
+        ind_end = s.find(']')
+        if ind_end == -1:
+            raise ValueError("Indices array should end with ')'")
+        ind_list = s[ind_start + 1: ind_end].split(',')
+        try:
+            indices = [int(ind) for ind in ind_list]
+        except ValueError:
+            raise ValueError("Unabel to parse indices.")
+        s = s[ind_end + 1:].strip()
+
+        val_start = s.find('[')
+        if val_start == -1:
+            raise ValueError("Values array should start with '('.")
+        val_end = s.find(']')
+        if val_end == -1:
+            raise ValueError("Values array should end with ')'.")
+        val_list = s[val_start + 1: val_end].split(',')
+        try:
+            values = [float(val) for val in val_list]
+        except ValueError:
+            raise ValueError("Unable to parse values.")
         return SparseVector(size, indices, values)
 
     def dot(self, other):
@@ -704,7 +736,7 @@ def stringify(vector):
         return str(vector)
 
     @staticmethod
-    def squared_distance(a, b):
+    def squared_distance(v1, v2):
         """
         Squared distance between two vectors.
         a and b can be of type SparseVector, DenseVector, np.ndarray
@@ -715,25 +747,36 @@ def squared_distance(a, b):
         >>> a.squared_distance(b)
         51.0
         """
-        a, b = _convert_to_vector(a), _convert_to_vector(b)
-        return a.squared_distance(b)
+        v1, v2 = _convert_to_vector(v1), _convert_to_vector(v2)
+        return v1.squared_distance(v2)
 
     @staticmethod
-    def norm(vec, p):
+    def norm(vector, p):
         """
         Find norm of the given vector.
         """
-        return _convert_to_vector(vec).norm(p)
+        return _convert_to_vector(vector).norm(p)
 
     @staticmethod
-    def parse(vectorString):
-        if vectorString.find('(') == -1:
-            return DenseVector.parse(vectorString)
-        return SparseVector.parse(vectorString)
+    def parse(s):
+        """Parse a string representation back into the Vector.
+
+        >>> Vectors.parse('[2,1,2 ]')
+        DenseVector([2.0, 1.0, 2.0])
+        >>> Vectors.parse(' ( 100,  [0],  [2])')
+        SparseVector(100, {0: 2.0})
+        """
+        if s.find('(') == -1 and s.find('[') != -1:
+            return DenseVector.parse(s)
+        elif s.find('(') != -1:
+            return SparseVector.parse(s)
+        else:
+            raise ValueError(
+                "Cannot find tokens '[' or '(' from the input string.")
 
     @staticmethod
-    def zeros(num):
-        return DenseVector(np.zeros(num))
+    def zeros(size):
+        return DenseVector(np.zeros(size))
 
 
 class Matrix(object):
diff --git a/python/pyspark/mllib/tests.py b/python/pyspark/mllib/tests.py
index 2dfd62676ab2e..36a4c7a5408c6 100644
--- a/python/pyspark/mllib/tests.py
+++ b/python/pyspark/mllib/tests.py
@@ -227,6 +227,8 @@ def test_parse_vector(self):
         a = SparseVector(4, [0, 2], [3, 4])
         self.assertTrue(str(a), '(4,[0,2],[3.0,4.0])')
         self.assertTrue(Vectors.parse(str(a)), a)
+        a = SparseVector(10, [0, 1], [4, 5])
+        self.assertTrue(SparseVector.parse(' (10, [0,1 ],[ 4.0,5.0] )'), a)
 
     def test_norms(self):
         a = DenseVector([0, 2, 3, -1])