[ARROW-7031] [Python] Expose the offsets of a ListArray in python

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.16.0
• Component/s: Python
• Labels: pull-request-available
• External issue URL: https://github.com/apache/arrow/issues/23342
• Assignee: Joris Van den Bossche
• Reporter: Joris Van den Bossche
• Created: 30/Oct/19 13:44
• Updated: 11/Jan/23 07:51
• Resolved: 05/Nov/19 17:29

Description

Assume the following ListArray:

In [1]: arr = pa.ListArray.from_arrays(offsets=[0, 3, 5], values=[1, 2, 3, 4, 5])                                                                                                                                  

In [2]: arr                                                                                                                                                                                                        
Out[2]: 
<pyarrow.lib.ListArray object at 0x7f11de71c708>
[
  [
    1,
    2,
    3
  ],
  [
    4,
    5
  ]
]

You can get the actual values as a flat array through .values / .flatten(), but there is currently no easy way to get back to the offsets (except from interpreting the buffers manually).

We should probably add an offsets attribute (there is actually also a TODO comment for that).

Issue Links

• links to: GitHub Pull Request #5759
• links to: GitHub Pull Request #5784