# Buggy code
def _gen_shuffle_chunks(cls, op, out_shape, shuffle_on, df):
    # gen map chunks
    map_chunks = []
    for chunk in df.chunks:
        map_op = DataFrameMergeAlignMap(
            shuffle_on=shuffle_on,
            sparse=chunk.issparse(),
            index_shuffle_size=out_shape[0],
        )
        map_chunks.append(
            map_op.new_chunk(
                [chunk],
                shape=(np.nan, np.nan),
                dtypes=chunk.dtypes,
                index=chunk.index,
                index_value=chunk.index_value,
                columns_value=chunk.columns,
            )
        )

    proxy_chunk = DataFrameShuffleProxy(object_type=ObjectType.dataframe).new_chunk(
        map_chunks,
        shape=(),
        dtypes=df.dtypes,
        index_value=df.index_value,
        columns_value=df.columns,
    )

    # gen reduce chunks
    reduce_chunks = []
    for out_idx in itertools.product(*(range(s) for s in out_shape)):
        reduce_op = DataFrameMergeAlignReduce(
            sparse=proxy_chunk.issparse(),
            shuffle_key=",".join(str(idx) for idx in out_idx),
        )
        reduce_chunks.append(
            reduce_op.new_chunk(
                [proxy_chunk],
                shape=(np.nan, np.nan),
                dtypes=proxy_chunk.dtypes,
                index=out_idx,
                index_value=proxy_chunk.index_value,
                columns_value=proxy_chunk.columns,
            )
        )
    return reduce_chunks


# Traceback (Exception)
In [28]: df = md.DataFrame(np.random.rand(10, 2))

In [29]: df + np.random.rand(10, 2)
---------------------------------------------------------------------------
Exception                                 Traceback (most recent call last)
<ipython-input-29-4a212df011a8> in <module>
----> 1 df + np.random.rand(10, 2)

~/Documents/mars_dev/mars/mars/dataframe/utils.py in wrapper(*args, **kwargs)
613     def wrapper(*args, **kwargs):
614         try:
--> 615             return func(*args, **kwargs)
616         except NotImplementedError:
617             return NotImplemented

~/Documents/mars_dev/mars/mars/dataframe/arithmetic/add.py in add(df, other, axis, level, fill_value)
33
34 def add(df, other, axis='columns', level=None, fill_value=None):
---> 35     other = wrap_sequence(other)
36     op = DataFrameAdd(axis=axis, level=level, fill_value=fill_value, lhs=df, rhs=other)
37     return op(df, other)

~/Documents/mars_dev/mars/mars/dataframe/utils.py in wrap_sequence(seq)
606
607     if isinstance(seq, (list, tuple, np.ndarray, TENSOR_TYPE)):
--> 608         seq = Series(seq)
609     return seq
610

~/Documents/mars_dev/mars/mars/dataframe/initializer.py in __init__(self, data, index, dtype, name, copy, chunk_size, gpu, sparse)
46             series = data
47         else:
---> 48             pd_series = pd.Series(data, index=index, dtype=dtype, name=name, copy=copy)
49             series = from_pandas_series(pd_series, chunk_size=chunk_size, gpu=gpu, sparse=sparse)
50         super(Series, self).__init__(series.data)

~/miniconda3/lib/python3.7/site-packages/pandas/core/series.py in __init__(self, data, index, dtype, name, copy, fastpath)
312                     data = data.copy()
313             else:
--> 314                 data = sanitize_array(data, index, dtype, copy, raise_cast_failure=True)
315
316                 data = SingleBlockManager(data, index, fastpath=True)

~/miniconda3/lib/python3.7/site-packages/pandas/core/internals/construction.py in sanitize_array(data, index, dtype, copy, raise_cast_failure)
727     elif subarr.ndim > 1:
728         if isinstance(data, np.ndarray):
--> 729             raise Exception("Data must be 1-dimensional")
730         else:
731             subarr = com.asarray_tuplesafe(data, dtype=dtype)

Exception: Data must be 1-dimensional

# Fixed code
def _gen_shuffle_chunks(cls, op, out_shape, shuffle_on, df):
    # gen map chunks
    map_chunks = []
    for chunk in df.chunks:
        map_op = DataFrameMergeAlignMap(
            shuffle_on=shuffle_on,
            sparse=chunk.issparse(),
            index_shuffle_size=out_shape[0],
        )
        map_chunks.append(
            map_op.new_chunk(
                [chunk],
                shape=(np.nan, np.nan),
                dtypes=chunk.dtypes,
                index=chunk.index,
                index_value=chunk.index_value,
                columns_value=chunk.columns_value,
            )
        )

    proxy_chunk = DataFrameShuffleProxy(object_type=ObjectType.dataframe).new_chunk(
        map_chunks,
        shape=(),
        dtypes=df.dtypes,
        index_value=df.index_value,
        columns_value=df.columns_value,
    )

    # gen reduce chunks
    reduce_chunks = []
    for out_idx in itertools.product(*(range(s) for s in out_shape)):
        reduce_op = DataFrameMergeAlignReduce(
            sparse=proxy_chunk.issparse(),
            shuffle_key=",".join(str(idx) for idx in out_idx),
        )
        reduce_chunks.append(
            reduce_op.new_chunk(
                [proxy_chunk],
                shape=(np.nan, np.nan),
                dtypes=proxy_chunk.dtypes,
                index=out_idx,
                index_value=proxy_chunk.index_value,
                columns_value=proxy_chunk.columns_value,
            )
        )
    return reduce_chunks