CODEWITHSUNDEEP
pythonpython-3.xpandasnumpydataframe
Marcos Santana
Marcos Santana

Reputation: 951

Convert list of arrays to pandas dataframe

I have a list of numpy arrays that I'm trying to convert to DataFrame. Each array should be a row of the dataframe.

Using pd.DataFrame() isn't working. It always gives the error: ValueError: Must pass 2-d input.

Is there a better way to do this?

This is my current code:

list_arrays = [ array([[0, 0, 0, 1, 0, 0, 0, 0, 00]], dtype='uint8'), 
                array([[0, 0, 3, 2, 0, 0, 0, 0, 00]], dtype='uint8')
              ]

d = pd.DataFrame(list_arrays)

ValueError: Must pass 2-d input

Upvotes: 23

Views: 77321

Answers (4)

BENY
BENY

Reputation: 323226

You can using pd.Series

pd.Series(l).apply(lambda x : pd.Series(x[0]))
Out[294]: 
   0  1  2  3  4  5  6  7  8
0  0  0  0  1  0  0  0  0  0
1  0  0  3  2  0  0  0  0  0

Upvotes: 4

MaxU - stand with Ukraine
MaxU - stand with Ukraine

Reputation: 210832

Option 1:

In [143]: pd.DataFrame(np.concatenate(list_arrays))
Out[143]:
   0  1  2  3  4  5  6  7  8
0  0  0  0  1  0  0  0  0  0
1  0  0  3  2  0  0  0  0  0

Option 2:

In [144]: pd.DataFrame(list(map(np.ravel, list_arrays)))
Out[144]:
   0  1  2  3  4  5  6  7  8
0  0  0  0  1  0  0  0  0  0
1  0  0  3  2  0  0  0  0  0

Why do I get:

ValueError: Must pass 2-d input

I think pd.DataFrame() tries to convert it to NDArray like as follows:

In [148]: np.array(list_arrays)
Out[148]:
array([[[0, 0, 0, 1, 0, 0, 0, 0, 0]],

       [[0, 0, 3, 2, 0, 0, 0, 0, 0]]], dtype=uint8)

In [149]: np.array(list_arrays).shape
Out[149]: (2, 1, 9)     # <----- NOTE: 3D array

Upvotes: 28

piRSquared
piRSquared

Reputation: 294218

Alt 1

pd.DataFrame(sum(map(list, list_arrays), []))

   0  1  2  3  4  5  6  7  8
0  0  0  0  1  0  0  0  0  0
1  0  0  3  2  0  0  0  0  0

Alt 2

pd.DataFrame(np.row_stack(list_arrays))

   0  1  2  3  4  5  6  7  8
0  0  0  0  1  0  0  0  0  0
1  0  0  3  2  0  0  0  0  0

Upvotes: 8

jpp
jpp

Reputation: 164623

Here is one way.

import numpy as np, pandas as pd

lst = [np.array([[0, 0, 0, 1, 0, 0, 0, 0, 0]], dtype=int),
       np.array([[0, 0, 3, 2, 0, 0, 0, 0, 0]], dtype=int)]

df = pd.DataFrame(np.vstack(lst))

#    0  1  2  3  4  5  6  7  8
# 0  0  0  0  1  0  0  0  0  0
# 1  0  0  3  2  0  0  0  0  0

Upvotes: 3

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