to_html function fail when max_rows is specified

[pilollipietro]

The error is:
list index out of range
Exception Location: /home/pietro/lod4statenv/local/lib/python2.7/site-packages/pandas/core/format.py in _write_body, line 923

In order to fix it I have replaced line 922 from:

for i in range(len(self.frame)):

to:

for i in range(min(len(self.frame), self.max_rows)):

[onesandzeroes]

Can you write up some short example code that will reproduce the issue? Preferably code that's simple and self-contained enough that people can just copy-paste into a Python console to see the issue for themselves.

[pilollipietro]

Of course:

import pandas as pd
import numpy as np
df = pd.DataFrame({'a': np.arange(10), 'b': np.random.randn(10)})
df.to_html(index=False,max_rows=3)

[onesandzeroes]

Hmmm, I think the fix for this one is actually a little bit more complicated than you've outlined (although you're definitely right to have noticed that max_rows should have been used in there somewhere rather than just using len(self.frame).

The bug you've found only occurs when index=False, and when index=True there's a lot more work going on to print a nice truncated version of the dataframe. None of that truncation seems to happen currently when index=False. Probably need to carefully go over all the things that are being done when index=True and make sure that the same things happen in this case. It gets even more complicated when we have a hierarchical index, so I might try and fix the single index case first and then see where we are.

Here's some extra test code if people want to compare the index=False case to index=True:

import pandas as pd
import numpy as np

df = pd.DataFrame({'a': np.arange(10), 'b': np.random.randn(10)})


print(df.to_html(max_rows=3))
print(df.to_html(index=False, max_rows=3))


# Hierarchical index cases
cols = pd.MultiIndex.from_tuples([('a', 'x'), ('a', 'y'), ('b', 'x'), ('b', 'y')])
index = pd.MultiIndex.from_arrays([
    [1, 1, 1, 1, 1, 2, 2, 2, 2, 2],
    ['foo', 'bar', 'foo', 'bar', 'foo', 'bar', 'foo', 'bar', 'foo', 'bar']
])
df2 = pd.DataFrame(np.random.randn(10, 4), columns=cols, index=index)
print(df2)
print(df2.to_html(max_rows=3))
print(df2.to_html(index=False, max_rows=3))

[jreback]

closing as stale. pls reopen if still an issue.