How to extract numpy arrays from specific column in pandas frame and stack them as a single numpy array

Question

I have a pandas frame like this.

pd.DataFrame(data={'name':['name1','name2'],'vector':[np.array([1,2,3,4]),np.array([12,22,34,4])]})

I want to extract the vectors from the frame as a matrix like this.

np.array([[1,2,3,4],[12,22,34,4]])

score 3 · Accepted Answer · answered May 10 '17 at 00:41

3

np.array(df['vector'].tolist())

will result in

array([[ 1,  2,  3,  4],
       [12, 22, 34,  4]])

or

df['vector'].as_matrix()

will result in

array([array([1, 2, 3, 4]), array([12, 22, 34,  4])], dtype=object)

answered May 10 '17 at 00:41

plasmon360

score 2 · Answer 2 · answered May 10 '17 at 01:59

2

df.vector.values should be the shortest.

answered May 10 '17 at 01:59

Chih-Hsu Jack Lin

2 Answers2