Deprecated dtype argument in Block.make_block_same_class

[TomAugspurger]

Just FYI,

In [1]: import warnings
In [2]: import fastparquet
In [3]: warnings.simplefilter('always', DeprecationWarning)
In [6]: import pandas as pd
In [7]: fastparquet.dataframe.empty([pd.DatetimeTZDtype(tz="UTC")], 10, cols=['a'], timezones={'a': 'UTC'})
/Users/taugspurger/Envs/dask-dev/lib/python3.7/site-packages/pandas/core/internals/blocks.py:231: DeprecationWarning: dtype argument is deprecated, will be removed in a future release.
  "in a future release.", DeprecationWarning)
Out[7]:
(                                    a
 0 2152-09-02 23:52:03.034234880+00:00
 1 2079-08-09 02:21:19.214470707+00:00
 2 1970-01-01 00:00:04.840882181+00:00
 3 1970-01-01 00:00:04.840938992+00:00
 4 1970-01-01 00:00:04.840939184+00:00
 5 1970-01-01 00:00:04.583459448+00:00
 6 1970-01-01 00:00:04.840968304+00:00
 7 1970-01-01 00:00:04.538786008+00:00
 8 1970-01-01 00:00:04.840968560+00:00
 9 1970-01-17 06:56:19.724521968+00:00,
 {'a': array(['2152-09-02T23:52:03.034234880', '2079-08-09T02:21:19.214470707',
         '1970-01-01T00:00:04.840882181', '1970-01-01T00:00:04.840938992',
         '1970-01-01T00:00:04.840939184', '1970-01-01T00:00:04.583459448',
         '1970-01-01T00:00:04.840968304', '1970-01-01T00:00:04.538786008',
         '1970-01-01T00:00:04.840968560', '1970-01-17T06:56:19.724521968'],
        dtype='datetime64[ns]')})

I think something like this should work.

ipdb> pp block.make_block_same_class(type(block.values)(values, dtype=block.values.dtype))
DatetimeTZBlock: slice(0, 1, 1), 1 x 10, dtype: datetime64[ns, UTC]

[martindurant]

Can you check against master? I thought I had already done this.

[TomAugspurger]

Same thing

fastparquet/fastparquet/dataframe.py

Lines 174 to 178 in 6c20042

	elif getattr(block.dtype, 'tz', None):
	new_shape = (size, )
	values = np.empty(shape=new_shape, dtype='M8[ns]')
	new_block = block.make_block_same_class(
	values=values, dtype=block.values.dtype)

[martindurant]

Clearly I must have fixed a different deprecation.

[jbrockmendel]

xref pandas-dev/pandas#27170

[jorisvandenbossche]

Clearly I must have fixed a different deprecation.

The original issue is #297, but I don't see a commit or PR referencing it that would have fixed it