DOC: "justify" parameter in to_html

[gfyoung]

The Travis docs for to_html states that the only accepted parameters for justify are left and right.

However, I stumbled upon the fact that you can also pass in center, and it will work just fine (i.e. the cell elements and headers are centered), as evidenced by the code:

pandas/pandas/io/formats/format.py

Lines 1215 to 1217 in fa557f7

	style = "text-align: {just};".format(just=self.fmt.justify)
	row.extend([single_column_table(c, self.fmt.justify, style)
	for c in self.columns])

@TomAugspurger : Should we continue to allow only left and right or should we expand to accept center ? I'm personally up for the latter but wanted to get consensus first.

[TomAugspurger]

Presumably all these work? https://developer.mozilla.org/en-US/docs/Web/CSS/text-align

+1 for anything that’s valid html / css

[gfyoung]

@TomAugspurger : I believe that's only a subset according to pandas 😉

df = DataFrame()
print(df.to_html(justify="augspurger"))  # your name is also valid

<table border="1" class="dataframe">
  <thead>
    <tr style="text-align: augspurger;">
      <th></th>
    </tr>
  </thead>
  <tbody>
  </tbody>
</table>

[gfyoung]

Looks like we need to do some validation on the justify parameter.