pandas: HTML output with conditional formatting

Question

I am trying to format a table, such that data in each column are formatted in a style depending on their values (similar to conditional formatting in spreadsheet programs).

Answer 1

Since pandas 0.17.1, it is easy to apply custom formatting to the data frame HTML representation using the styling api.

import pandas as pd

df = pd.DataFrame({
    'correlation':[0.5, 0.1,0.9],
    'p_value':[0.1,0.8,0.01]})
styled_df = df.style.apply(
    lambda x: ['font-weight: bold; background-color: yellow'
               if value <= 0.01 else '' for value in x])
styled_df

The output is rendered automatically in interfaces such as the Jupyter Notebook and the string representation of the HTML can be returned with the render() method.

print(styled_df.render())

<style  type="text/css" >
    #T_4e49b9da_8451_11e8_9166_605718a99a7frow2_col1 {
            font-weight:  bold;
             background-color:  yellow;
            font-weight:  bold;
             background-color:  yellow;
        }</style>  
<table id="T_4e49b9da_8451_11e8_9166_605718a99a7f" > 
<thead>    <tr> 
        <th class="blank level0" ></th> 
        <th class="col_heading level0 col0" >correlation</th> 
        <th class="col_heading level0 col1" >p_value</th> 
    </tr></thead> 
<tbody>    <tr> 
        <th id="T_4e49b9da_8451_11e8_9166_605718a99a7flevel0_row0" class="row_heading level0 row0" >0</th> 
        <td id="T_4e49b9da_8451_11e8_9166_605718a99a7frow0_col0" class="data row0 col0" >0.5</td> 
        <td id="T_4e49b9da_8451_11e8_9166_605718a99a7frow0_col1" class="data row0 col1" >0.1</td> 
    </tr>    <tr> 
        <th id="T_4e49b9da_8451_11e8_9166_605718a99a7flevel0_row1" class="row_heading level0 row1" >1</th> 
        <td id="T_4e49b9da_8451_11e8_9166_605718a99a7frow1_col0" class="data row1 col0" >0.1</td> 
        <td id="T_4e49b9da_8451_11e8_9166_605718a99a7frow1_col1" class="data row1 col1" >0.8</td> 
    </tr>    <tr> 
        <th id="T_4e49b9da_8451_11e8_9166_605718a99a7flevel0_row2" class="row_heading level0 row2" >2</th> 
        <td id="T_4e49b9da_8451_11e8_9166_605718a99a7frow2_col0" class="data row2 col0" >0.9</td> 
        <td id="T_4e49b9da_8451_11e8_9166_605718a99a7frow2_col1" class="data row2 col1" >0.01</td> 
    </tr></tbody> 
</table>

Answer 2

You can use the DataFrame to_html method, which comes with formatters argument.

An easier solution would be to surround by <span class="significant"> and </span>, (rather than *). Note: by default this will be escaped (i.e. < becomes <) so you will need to use the escape=False argument.