Merge branch 'master' into feature-persistence

awkward/array/jagged.py

@@ -164,6 +164,26 @@ def fromuniques(cls, uniques, content):
         out._parents = parents
         return out
 
+    @classmethod
+    def fromindex(cls, index, content, validate=True):
+        index = awkward.util.toarray(index, awkward.util.INDEXTYPE, awkward.util.numpy.ndarray)
+        if isinstance(index, JaggedArray):
+            index = index.content
+        if not issubclass(index.dtype.type, awkward.util.numpy.integer):
+            raise TypeError("index must have integer dtype")
+        if len(index.shape) != 1 or len(index) != len(content):
+            raise ValueError("index array must be one-dimensional with the same length as content")
+
+        if validate:
+            if not ((index[1:] - index[:-1])[(index != 0)[1:]] == 1).all():
+                raise ValueError("every index that is not zero must be one greater than the previous")
+
+        starts = awkward.util.numpy.nonzero(index == 0)[0]
+        offsets = awkward.util.numpy.empty(len(starts) + 1, dtype=awkward.util.INDEXTYPE)
+        offsets[:-1] = starts
+        offsets[-1] = len(index)
+        return cls.fromoffsets(offsets, content)
+
     @classmethod
     def fromjagged(cls, jagged):
         jagged = jagged._tojagged(copy=False)

awkward/array/union.py

@@ -42,16 +42,17 @@ def __init__(self, tags, index, contents):
     def fromtags(cls, tags, contents):
         out = cls.__new__(cls)
         out.tags = tags
-        out.index = awkward.util.numpy.empty(out._tags.shape, dtype=awkward.util.INDEXTYPE)
         out.contents = contents
 
         if len(out._tags.reshape(-1)) > 0 and out._tags.reshape(-1).max() >= len(out._contents):
             raise ValueError("maximum tag is {0} but there are only {1} contents arrays".format(out._tags.reshape(-1).max(), len(out._contents)))
 
+        index = awkward.util.numpy.full(out._tags.shape, -1, dtype=awkward.util.INDEXTYPE)
         for tag, content in enumerate(out._contents):
             mask = (out._tags == tag)
-            out._index[mask] = awkward.util.numpy.arange(awkward.util.numpy.count_nonzero(mask))
+            index[mask] = awkward.util.numpy.arange(awkward.util.numpy.count_nonzero(mask))
 
+        out.index = index
         return out
 
     def copy(self, tags=None, index=None, contents=None):

tests/test_jagged.py

@@ -69,6 +69,12 @@ def test_jagged_type(self):
         a = JaggedArray([0, 3, 3, 5], [3, 3, 5, 10], [[0.0], [1.1], [2.2], [3.3], [4.4], [5.5], [6.6], [7.7], [8.8], [9.9]])
         assert a.type == ArrayType(4, numpy.inf, 1, float)
 
+    def test_jagged_fromindex(self):
+        a = JaggedArray.fromindex([0, 1, 0, 0, 0, 1, 2, 0, 1, 0], [0.0, 1.1, 2.2, 3.3, 4.4, 5.5, 6.6, 7.7, 8.8, 9.9])
+        self.assertEqual(a.tolist(), [[0.0, 1.1], [2.2], [3.3], [4.4, 5.5, 6.6], [7.7, 8.8], [9.9]])
+        self.assertEqual(a.starts.tolist(), [0, 2, 3, 4, 7, 9])
+        self.assertEqual(a.stops.tolist(), [2, 3, 4, 7, 9, 10])
+
     def test_jagged_str(self):
         pass