>>> import pandas as pd
>>> df = pd.DataFrame({"A":[1, 2], "B":[3, 4], "C":[5, 6]})
>>> df
A B C
0 1 3 5
1 2 4 6
>>> s_array = df[["A", "B", "C"]].to_numpy()
>>> s_array
array([[1, 3, 5],
[2, 4, 6]])
>>> t_array = df[["B", "C"]].to_numpy()
>>> print (t_array)
[[3 5]
[4 6]]
df['col1'] = df['col1'].apply(lambda x: np.array(x))
type(df['col1'].iloc[0])
numpy.ndarray