IndexError: tuple index out of range after upgrade to 0.25 · Issue #27775 · pandas-dev/pandas (original) (raw)

Root cause (in both cases using df = pd.DataFrame({'a': [1, 2, 3]})):

In [71]: pd.__version__  
Out[71]: '0.25.0'

In [73]: df.index[:, None]
Out[73]: Int64Index([0, 1, 2], dtype='int64')

In [74]: df.index[:, None].shape
Out[74]: (3,)

vs

In [10]: pd.__version__  
Out[10]: '0.24.2'

In [13]: df.index[:, None] 
Out[13]: Int64Index([0, 1, 2], dtype='int64')

In [14]: df.index[:, None].shape
Out[14]: (3, 1)

So before, indexing with [:, None] (in numpy a way to add a dimension to get 2D array) actually resulting in Index with ndim of 2 (but which is of course inconsistent state of the Index object)

Matplotlib relied on this fact when an Index is passed to plt.plot, as reported in matplotlib/matplotlib#14992

I have explained the issue here and here in details. Basically, after upgrading to the version 0.25 I got the error:

IndexError: tuple index out of range

while attempting to plot a CSV file.