从熊猫数据框中提取Numpy数组作为矩阵

Question

I ended up with the following data structure:

import numpy as np
import pandas as pd

my_df = pd.DataFrame({'col_1': [1,2,3]})
my_df['col_1'] = my_df['col_1'].apply(lambda x: np.array([1,2,3]))
my_df.as_matrix()

it looks like this:

array([[array([1, 2, 3])],
       [array([1, 2, 3])],
       [array([1, 2, 3])]], dtype=object)

Whily I would like it to look like simply numpy matrix. Any thoughts?

Answer 1

If you just want an array, you can

np.array(my_df.col_1.tolist())

array([[1, 2, 3],
       [1, 2, 3],
       [1, 2, 3]])