Pandas DataFrame column values in to list

Question

I have a pandas DataFrame like following

                          clusters
0                              [4]
1                  [9, 14, 16, 19]
2           [6, 7, 10, 17, 18, 20]
3  [1, 2, 3, 5, 8, 11, 12, 13, 15]

I need to get only the integer values in the cluster column separately. Like following(This can be four lists no need of having another DataFrame)

0                              4
1                  9, 14, 16, 19
2           6, 7, 10, 17, 18, 20
3  1, 2, 3, 5, 8, 11, 12, 13, 15

I tried different things. Could not achieve the expected output.

In [36]: clustlist = list(firstclusters.clusters.values)
Out[36]:   
    [array([4]), array([ 9, 14, 16, 19]), array([ 6,  7, 10, 17, 18, 20]), array([ 1,  2,  3,  5,  8, 11, 12, 13, 15])]

In [37]: np.ravel(clustlist)
Out[37]:
    [array([4]) array([ 9, 14, 16, 19]) array([ 6,  7, 10, 17, 18, 20])
     array([ 1,  2,  3,  5,  8, 11, 12, 13, 15])]

In [38]: np.hstack(clustlist)
Out[38]:
    [ 4  9 14 16 19  6  7 10 17 18 20  1  2  3  5  8 11 12 13 15]

The obvious question: why? :0

Andy Hayden
– Andy Hayden

2014-03-06 06:00:51 +00:00
Commented Mar 6, 2014 at 6:00 — Andy Hayden
– Andy Hayden, Commented Mar 6, 2014 at 6:00

Andy Hayden · Accepted Answer · 2014-03-06 05:56:54Z

8

If each item is just a list, you can use the tolist Series method:

In [11]: df.clusters.tolist()
Out[11]: [[4], [9, 14, 16, 19], [6, 7, 10, 17, 18, 20], [1, 2, 3, 5, 8, 11, 12, 13, 15]]

Or, if these are numpy arrays you need to apply tolist to each item first:

In [12]: df.clusters.apply(np.ndarray.tolist).tolist()
Out[12]: [[4], [9, 14, 16, 19], [6, 7, 10, 17, 18, 20], [1, 2, 3, 5, 8, 11, 12, 13, 15]]

answered Mar 6, 2014 at 5:56

Andy Hayden

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1 Comment

Nilani Algiriyage Over a year ago

Output of tolist() is similar to the one that I get from the In [36]: [array([4]), array([ 9, 14, 16, 19]), array([ 6, 7, 10, 17, 18, 20]), array([ 1, 2, 3, 5, 8, 11, 12, 13, 15])]

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