For example
import pandas as pd
d1 = pd.Series(['a b', 'c d'])
t1 = d1.str.split()
a1 = t1.values
where a1 would be
array([list(['a', 'b']), list(['c', 'd'])], dtype=object)
how to transform it to
array([['a', 'b'],
['c', 'd']], dtype='<U1')