can't convert a pd.DataFrame with all empty string to ctable

[rabbit8ge]

like:

bcolz.ctable.fromdataframe(pd.DataFrame({'a':[1,2,3],'b':['','','']}))
D:\Anaconda2\lib\site-packages\bcolz\ctable.py:693: FutureWarning: pandas.lib is deprecated and will be removed in a future version.
You can access infer_dtype as pandas.api.types.infer_dtype
inferred_type = pd.lib.infer_dtype(vals)
Traceback (most recent call last):
File "", line 1, in
File "D:\Anaconda2\lib\site-packages\bcolz\ctable.py", line 703, in fromdataframe
(dtype, maxitemsize), **ckwargs)
File "bcolz/carray_ext.pyx", line 1063, in bcolz.carray_ext.carray.cinit (bcolz\carray_ext.c:14817)
File "bcolz/carray_ext.pyx", line 1146, in bcolz.carray_ext.carray._create_carray (bcolz\carray_ext.c:15653)
File "bcolz/carray_ext.pyx", line 1094, in bcolz.carray_ext.carray._adapt_dtype (bcolz\carray_ext.c:15193)
ValueError: invalid itemsize in generic type tuple