Random seg fault with groupby #2113
Description
I came across this seg fault when I was trying to figure out the syntax to get column means. The below example triggers the seg fault, but strangely only about 30% of the time. About 10% of the time I get a reasonable error. The randomness of the result is very strange to me because the same command was run every time!
I am using the latest pandas and numpy from git. I have ECC memory and have never seen any hardware triggered issues.
$ python
Python 3.2.2 (default, Mar 9 2012, 14:43:22)
[GCC 4.4.4 20100726 (Red Hat 4.4.4-13)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import pandas
>>> pandas.DataFrame({'x': [1,2,3], 'y': [3,4,5]}).groupby(level=0, axis='columns').mean()
Segmentation fault
$ python
Python 3.2.2 (default, Mar 9 2012, 14:43:22)
[GCC 4.4.4 20100726 (Red Hat 4.4.4-13)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import pandas
>>> pandas.DataFrame({'x': [1,2,3], 'y': [3,4,5]}).groupby(level=0, axis='columns').mean()
0 1 2
x 1 2 3
y 3 4 5
>>> pandas.DataFrame({'x': [1,2,3], 'y': [3,4,5]}).groupby(level=0, axis='columns').mean()
0 1 2
x 1 2 3
y 3 4 5
>>> pandas.DataFrame({'x': [1,2,3], 'y': [3,4,5]}).groupby(level=0, axis='columns').mean()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/usr/local/lib/python3.2/site-packages/pandas-0.9.1.dev_ebcbd33-py3.2-linux-x86_64.egg/pandas/core/generic.py", line 134, in groupby
sort=sort, group_keys=group_keys)
File "/usr/local/lib/python3.2/site-packages/pandas-0.9.1.dev_ebcbd33-py3.2-linux-x86_64.egg/pandas/core/groupby.py", line 481, in groupby
return klass(obj, by, **kwds)
File "/usr/local/lib/python3.2/site-packages/pandas-0.9.1.dev_ebcbd33-py3.2-linux-x86_64.egg/pandas/core/groupby.py", line 146, in __init__
grouper, exclusions = _get_grouper(obj, keys, axis=axis,
IndexError: tuple index out of range
>>> pandas.DataFrame({'x': [1,2,3], 'y': [3,4,5]}).groupby(level=0, axis='columns').mean()
Segmentation fault