Check schema with Decimal not working in Pandera

[tpcgold]

Seems like it's not possible to check a decimal with pandera schema:

import pandera as pa

schema = pa.DataFrameSchema({
    'sample': pa.Column(
        pa.Decimal(precision=13, scale=2))
})

Traceback (most recent call last):
  File "G:\My Drive\PycharmProjects\Development\venv\lib\site-packages\pandera\engines\pandas_engine.py", line 153, in dtype
    return engine.Engine.dtype(cls, data_type)
  File "G:\My Drive\PycharmProjects\Development\venv\lib\site-packages\pandera\engines\engine.py", line 210, in dtype
    raise TypeError(
TypeError: Data type 'Decimal(13, 2)' not understood by Engine.
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
  File "C:\Users\stefa\AppData\Local\Programs\Python\Python39\lib\code.py", line 90, in runcode
    exec(code, self.locals)
  File "<input>", line 108, in <module>
  File "G:\My Drive\PycharmProjects\Development\venv\lib\site-packages\pandera\schema_components.py", line 81, in __init__
    super().__init__(
  File "G:\My Drive\PycharmProjects\Development\venv\lib\site-packages\pandera\schemas.py", line 1713, in __init__
    self.dtype = dtype  # type: ignore
  File "G:\My Drive\PycharmProjects\Development\venv\lib\site-packages\pandera\schemas.py", line 1820, in dtype
    self._dtype = pandas_engine.Engine.dtype(value) if value else None
  File "G:\My Drive\PycharmProjects\Development\venv\lib\site-packages\pandera\engines\pandas_engine.py", line 171, in dtype
    np_or_pd_dtype = pd.api.types.pandas_dtype(data_type)
  File "G:\My Drive\PycharmProjects\Development\venv\lib\site-packages\pandas\core\dtypes\common.py", line 1777, in pandas_dtype
    npdtype = np.dtype(dtype)
TypeError: Cannot interpret 'DataType(Decimal(13, 2))' as a data type

[tpcgold]

Altough this might work for some developers:

import pandera as pa

schema = pa.DataFrameSchema({
    'sample': pa.Column(
        Decimal)
})

Decimal(28,0) and others like for example Decimal(13,1) are not the same and should be covered by the schema check

[NathanEmb]

I encountered this issue as well, both when specifying a custom scale and when trying to use default values

[cosmicBboy]

This is definitely a bug!

Looking into a fix...

In the mean time, you can use the pandas_engine datatype here https://pandera.readthedocs.io/en/stable/reference/generated/pandera.engines.pandas_engine.Decimal.html#pandera.engines.pandas_engine.Decimal

import pandera as pa
from pandera.engines.pandas_engine import Decimal

schema = pa.DataFrameSchema({
    'sample': pa.Column(Decimal(13, 1))
})
print(schema)

[cosmicBboy]

@tpcgold @NathanEmb #956 should address this issue