如何从DataFrame创建整数列表？

Question

I have Data Frame:

Values    Values2
1,2,3,4   0,2,3
2,1,0,6   0,0,0
9,8,7,6   1,0,1

I want to create list of lists. I do that in following way:

df[['Values']].values.tolist()

In output a get:

[['1,2,3,4'],
 ['2,1,0,6'],
 ['9,8,7,6']]

It's a strings but I need a lists of integer like that:

 [[1,2,3,4],
  [2,1,0,6],
  [9,8,7,6]]

How can I do that?

Answer 1

It seems they are stored as a string. Try the following (not very robust, but depending on your context it can be ok):

slist = df[['Values']].values.tolist()
ilist = [ [int(s) for s in l[0].split(',')] for l in slist] 

Answer 2

You can use str.split to split the string on comma, with expand=True this will separate each value into it's own column, you can then convert the type to int and then get the values in a list as desired:

In [109]:
df['Values'].str.split(',',expand=True).astype(int).values.tolist()

Out[109]:
[[1, 2, 3, 4], [2, 1, 0, 6], [9, 8, 7, 6]]

Breaking this down:

In [110]:
df['Values'].str.split(',',expand=True)

Out[110]:
   0  1  2  3
0  1  2  3  4
1  2  1  0  6
2  9  8  7  6

In [111]:    
df['Values'].str.split(',',expand=True).astype(int).info()

<class 'pandas.core.frame.DataFrame'>
RangeIndex: 3 entries, 0 to 2
Data columns (total 4 columns):
0    3 non-null int32
1    3 non-null int32
2    3 non-null int32
3    3 non-null int32
dtypes: int32(4)
memory usage: 128.0 bytes

To handle NaN/None values use to_numeric with stack and unstack :

In [114]:
pd.to_numeric(df['Values'].str.split(',',expand=True).stack(), errors='coerce').unstack().values.tolist()

Out[114]:
[[1, 2, 3, 4], [2, 1, 0, 6], [9, 8, 7, 6]]