Python - Does Array.from_pandas allow for type casting where values are truncated?

[Bryan Cutler]

Hi devs,

I am creating a pyarrow.Array from a pandas.Series and when specifying the
data type, if the value will be truncated an error is raised.  For example:

import pyarrow as pa
import pandas as pd
s = pd.Series([pd.Timestamp(1)])
arr = pa.Array.from_pandas(s, type=pa.timestamp('us'))

/home/bryan/miniconda2/lib/python2.7/site-packages/pyarrow/error.pxi in
pyarrow.lib.check_status
(/arrow/python/build/temp.linux-x86_64-2.7/lib.cxx:8270)()
     75         message = frombytes(status.message())
     76         if status.IsInvalid():
---> 77             raise ArrowInvalid(message)
     78         elif status.IsIOError():
     79             raise ArrowIOError(message)

ArrowInvalid: Casting from timestamp[ns] to timestamp[us] would lose data: 1


If I do the casting after creating the pyarrow.Array like

pa.Array.from_pandas(s).cast(pa.timestamp('us'), safe=False)

then it is fine.  My question is does pyarrow.Array.from_pandas only use
safe casting or is there a way to specify that truncation is ok?

Thanks,
Bryan