ENH: Enhance printing options for Styler: head and tail ?

[dennymarcels]

Is your feature request related to a problem?

More like an improvement.

Describe the solution you'd like

I just started playing around with pandas styling, and I noticed there is no way to print only the head and/or tail of a stylized DataFrame. It would be awesome if the styling could be applied to the whole df but then we could print only selected rows, like head and/or tail.

API breaking implications

I guess there could be a parameter passed to methods such as bar, or a new method to be appended to the end of a call.

Describe alternatives you've considered

I can apply the style to a slice of a DataFrame but then the styling function is applied to this slice only. What if I want to highlight_max to the whole df but print head/tail only?

[attack68]

Interesting idea.
After #41635, there are max_rows and max_cols mechanics which are expected to be added as keywords to: Styler.to_html(). Currently this is only equivalent to a head scenario. The parsing and rendering mechanics were quite complicated so the equivalent of a tail might be df[::-1].style.to_html(max_rows=100) for example.

Do comment on the PR or further if you have any good ideas.

I guess there could be a parameter passed to methods such as bar, or a new method to be appended to the end of a call.

Nope don't want to add kwargs where they are not relevant to the function, but more add kwargs to rendering methods, or add to styler.options namespace.

[dennymarcels]

To be more precise, I like it when I call the DataFrame as the last line of code in a Colab cell and only the first 5 and last 5 rows are rendered. I was thinking something along that idea.

It would be nice to be able to call df.stile.bar().head(), or df.stile.bar().tail(), or even df.stile.bar().headAndTail().

[attack68]

@dennymarcels please comment on #45176

[ivasve]

Hi @dennymarcels , did you have a look at issue #45176 if it has solved the issue you've been having?

[LinuxIsCool]

It's frustrating that max_rows can not be applied to a stylized dataframe.

[LinuxIsCool]

To deal with this for now, I just implemented this utility function in my code:

    def _truncate_dataframe(df, max_rows):
        return pd.concat([df.head(max_rows//2), df.tail(max_rows//2)])

[attack68]

The "stylized dataframe" discussed in this thread is actually a Styler class. Your utility function involves DataFrames and does not reference a Styler. For Styler have you considered the global pandas option styler.render.max_rows ? https://pandas.pydata.org/docs/user_guide/options.html#available-options

[LinuxIsCool]

Thanks @attack68 for the fast response. That did indeed help me, but there is still a nuance issue of the aesthetics of the truncation. I would like to see the head and tail of the dataframe rather than just the head as was pointed out by @dennymarcels in this thread.

Here is my example:

import pandas as pd
import panel as pn
pd.set_option('styler.render.max_rows', 5)

df = pd.DataFrame(list(range(20)))

# Define CSS style for the sapphire color on column 'A' header
styles = [
    {'selector': 'th.col_heading.level0.col0', 
     'props': [('background-color', 'blue'), ('color', 'white')]}
]

# Apply the style to the DataFrame
styled_df = df.style.set_table_styles(styles, overwrite=False)

styled_df

[attack68]

styled_df.hide(df.index[5:-5])

[attack68]

I don't think the API for Styler is going to be expanded to for the head and tail case, nor with a show method. I think the solution to use hide whilst initially unintuitive is actually the best way to utilise all of Styler chained procedures.

Will close this issue and relabel the title for anyone searching for similar.