BUG: MultiIndex truncated for some non-list arguments

pandas/compat/__init__.py

@@ -259,6 +259,8 @@ def set_function_name(f, name, cls):
         return f
 
     ResourceWarning = ResourceWarning
+
+    zip_longest = itertools.zip_longest
 
 else:
     string_types = basestring,
@@ -309,9 +311,30 @@ def set_function_name(f, name, cls):
 
     class ResourceWarning(Warning): pass
 
+    zip_longest = itertools.izip_longest
+
 string_and_binary_types = string_types + (binary_type,)
 
 
+class ABC(object):
+    if PY3:
+        from collections import abc
+        Container = abc.Container
+        Iterable = abc.Iterable
+        Iterator = abc.Iterator
+        Sequence = abc.Sequence
+        MutableSequence = abc.MutableSequence
+        Mapping = abc.Mapping
+    else:
+        import collections
+        Container = collections.Container
+        Iterable = collections.Iterable
+        Iterator = collections.Iterator
+        Sequence = collections.Sequence
+        MutableSequence = collections.MutableSequence
+        Mapping = collections.Mapping
+
+
 try:
     # callable reintroduced in later versions of Python
     callable = callable

pandas/indexes/multi.py

@@ -10,7 +10,7 @@
 import pandas.index as _index
 from pandas.lib import Timestamp
 
-from pandas.compat import range, zip, lrange, lzip, map
+from pandas.compat import range, zip, lrange, lzip, map, zip_longest, ABC
 from pandas.compat.numpy import function as nv
 from pandas import compat
 
@@ -916,19 +916,24 @@ def from_arrays(cls, arrays, sortorder=None, names=None):
 
         See Also
         --------
-        MultiIndex.from_tuples : Convert list of tuples to MultiIndex
+        MultiIndex.from_tuples : Convert sequence of tuples to MultiIndex
         MultiIndex.from_product : Make a MultiIndex from cartesian product
                                   of iterables
         """
+        try:
+            arrays = list(arrays)
+        except:
+            raise ValueError('arrays must be iterable/sequence')
+
         if len(arrays) == 1:
             name = None if names is None else names[0]
             return Index(arrays[0], name=name)
 
         # Check if lengths of all arrays are equal or not,
         # raise ValueError, if not
-        for i in range(1, len(arrays)):
-            if len(arrays[i]) != len(arrays[i - 1]):
-                raise ValueError('all arrays must be same length')
+        _len_first = len(arrays[0])
+        if not all(len(x) == _len_first for x in arrays):
+            raise ValueError('all arrays must be same length')
 
         from pandas.core.categorical import _factorize_from_iterables
 
@@ -942,7 +947,7 @@ def from_arrays(cls, arrays, sortorder=None, names=None):
     @classmethod
     def from_tuples(cls, tuples, sortorder=None, names=None):
         """
-        Convert list of tuples to MultiIndex
+        Convert sequence of tuples to MultiIndex
 
         Parameters
         ----------
@@ -964,24 +969,18 @@ def from_tuples(cls, tuples, sortorder=None, names=None):
 
         See Also
         --------
-        MultiIndex.from_arrays : Convert list of arrays to MultiIndex
+        MultiIndex.from_arrays : Convert sequence of arrays to MultiIndex
         MultiIndex.from_product : Make a MultiIndex from cartesian product
                                   of iterables
         """
-        if len(tuples) == 0:
-            # I think this is right? Not quite sure...
-            raise TypeError('Cannot infer number of levels from empty list')
-
-        if isinstance(tuples, (np.ndarray, Index)):
-            if isinstance(tuples, Index):
-                tuples = tuples._values
+        if isinstance(tuples, Index):
+            tuples = tuples._values
 
-            arrays = list(lib.tuples_to_object_array(tuples).T)
-        elif isinstance(tuples, list):
-            arrays = list(lib.to_object_array_tuples(tuples).T)
+        if isinstance(tuples, np.ndarray):
+            arrays = lib.tuples_to_object_array(tuples).T
         else:
-            arrays = lzip(*tuples)
-
+            arrays = zip_longest(*tuples)
+            
         return MultiIndex.from_arrays(arrays, sortorder=sortorder, names=names)
 
     @classmethod