convert python dataframe to list

17
votes

I have a Python dataFrame with multiple columns. 

  LogBlk    Page                                    BayFail       
  0          0                                 [0, 1, 8, 9]  
  1          16           [0, 1, 4, 5, 6, 8, 9, 12, 13, 14]  
  2          32           [0, 1, 4, 5, 6, 8, 9, 12, 13, 14]  
  3          48           [0, 1, 4, 5, 6, 8, 9, 12, 13, 14]

I want to find BayFails that is associated with LogBlk=0, and Page=0. 

df2 = df[ (df['Page'] == 16) & (df['LogBlk'] == 0) ]['BayFail']

This will return [0,1,8,9]

What I want to do is to convert this pandas.series into a list. Does anyone know how to do that?

2
pythonpython-3.xpython-2.7pandas

2 Answers

37
votes

pandas.Series, has a tolist method:

In [10]: import pandas as pd

In [11]: s = pd.Series([0,1,8,9], name = 'BayFail')

In [12]: s.tolist()
Out[12]: [0L, 1L, 8L, 9L]

Technical note: In my original answer I said that Series was a subclass of numpy.ndarray and inherited its tolist method. While that's true for Pandas version 0.12 or older, In the soon-to-be-released Pandas version 0.13, Series has been refactored to be a subclass of NDFrame. Series still has a tolist method, but it has no direct relationship to the numpy.ndarray method of the same name.

3
votes

You can also convert them to numpy arrays

In [124]: s = pd.Series([0,1,8,9], name='BayFail')

In [125]: a = pd.np.array(s)
Out[125]: array([0, 1, 8, 9], dtype=int64)

In [126]: a[0]
Out[126]: 0