how do i convert a numpy array to pandas dataframe

Question

How do i convert a numpy array to a pandas dataframe?

for example:

test = np.array([[1,2],[2,3]])
test2 = np.array([[2,4],[2,5]])

to this:

pd.DataFrame({'test':[[1,2],[2,3]],
              'test2':[[2,4],[2,5]]})

     test   test2
0  [1, 2]  [2, 4]
1  [2, 3]  [2, 5]

It would be much better to have four separate columns with each containing one integer. That way, you could take advantage of the efficient vectorised operations such as sum(), diff(), etc. — Alex Riley
– Alex Riley, Commented Apr 30, 2015 at 21:42
I want to have lists in them because I am going to create a new column from test and test2 — collarblind
– collarblind, Commented Apr 30, 2015 at 21:43
it would still be a better practice to modify your approach to deal with single values in separate columns. — Paul H
– Paul H, Commented Apr 30, 2015 at 22:25

unutbu · Accepted Answer · 2015-04-30 21:51:38Z

4

Although you could use

In [85]: pd.DataFrame({'test':test.tolist(), 'test2':test2.tolist()})
Out[85]: 
     test   test2
0  [1, 2]  [2, 4]
1  [2, 3]  [2, 5]

computation on the NumPy arrays would probably be much faster than an equivalent computation done on a Pandas DataFrame whose columns contain Python lists.

answered Apr 30, 2015 at 21:51

unutbu

886k197 gold badges1.9k silver badges1.7k bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Andy Hayden · Accepted Answer · 2015-04-30 23:41:21Z

0

If these numpy arrays have the same length, then Panel may be a preferable:

In [11]: p = pd.Panel({"test": test, "test2": test2})

In [12]: p
Out[12]:
<class 'pandas.core.panel.Panel'>
Dimensions: 2 (items) x 2 (major_axis) x 2 (minor_axis)
Items axis: test to test2
Major_axis axis: 0 to 1
Minor_axis axis: 0 to 1

In [13]: p["test"]  # a DataFrame
Out[13]:
   0  1
0  1  2
1  2  3

answered Apr 30, 2015 at 23:41

Andy Hayden

378k110 gold badges640 silver badges546 bronze badges

Collectives™ on Stack Overflow

how do i convert a numpy array to pandas dataframe

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related