exclude dask collections from meta check

dask/dataframe/tests/test_utils_dataframe.py

@@ -345,3 +345,6 @@ def test_is_dataframe_like():
     assert not is_index_like(df)
     assert not is_index_like(df.x)
     assert is_index_like(df.index)
+
+    ddf = dd.from_pandas(df, npartitions=1)
+    assert is_dataframe_like(ddf)

dask/dataframe/utils.py

@@ -18,6 +18,7 @@
     # pandas < 0.19.2
     from pandas.core.common import is_datetime64tz_dtype
 
+from ..base import is_dask_collection
 from ..compatibility import PY2, Iterator, Mapping
 from ..core import get_deps
 from ..local import get_sync
@@ -450,14 +451,17 @@ def _nonempty_series(s, idx=None):
 
 
 def is_dataframe_like(df):
+    """ Looks like a Pandas DataFrame """
     return set(dir(df)) > {'dtypes', 'columns', 'groupby', 'head'}
 
 
 def is_series_like(s):
+    """ Looks like a Pandas Series """
     return set(dir(s)) > {'name', 'dtype', 'groupby', 'head'}
 
 
 def is_index_like(s):
+    """ Looks like a Pandas Index """
     attrs = set(dir(s))
     return attrs > {'name', 'dtype'} and 'head' not in attrs
 
@@ -498,7 +502,8 @@ def equal_dtypes(a, b):
             return a == b
         return (a.kind in eq_types and b.kind in eq_types) or (a == b)
 
-    if not (is_dataframe_like(meta) or is_series_like(meta) or is_index_like(meta)):
+    if (not (is_dataframe_like(meta) or is_series_like(meta) or is_index_like(meta))
+            or is_dask_collection(meta)):
         raise TypeError("Expected partition to be DataFrame, Series, or "
                         "Index, got `%s`" % type(meta).__name__)