python - pandas styling doesn't display for all rows in large dataframes in Chrome or Edge

Question

Update:

• The issue seems to be with displaying the HTML with styling rendered by pandas in Google Chrome and Microsoft Edge.

• JupyterLab in Firefox correctly displays all of the styled rows and correctly renders an output HTML file.

• The updated questions are

  1. Why doesn't the HTML rendered by pandas completely display all the styling in Chrome or Edge?
  2. Is there a more efficient way to apply the styling done by pandas so the HTML also works in Chrome and Edge?

• Versions:

  • pandas v1.2.4
  • Chrome v90.0.4430.93 (Official Build) (64-bit)
  • Edge v90.0.818.56 (Official build) (64-bit)

Original:

• Questions - they are interrelated:
  1. Why aren't all of the rows displaying the background styling in Jupyter or writing to HTML?
     • All rows should have green styling, but the last 5 do not display the styling.
  2. How can all of the rows be made to display the background styling?
• Given a large dataframe, in this case 474 rows x 35 columns, the applied styling stops displaying.
  • 
• If the number of rows or columns increases beyond this size, then more rows aren't displayed.
• We can see from the styling map, that the rows are correctly mapped with a background color, but it isn't displayed.
  • 
• If the number of rows or columns is reduced, then all of the rows display the correct styling.
• Tested in jupyterlab v3.0.11
• Tested in PyCharm 2021.1 (Professional Edition) Build #PY-211.6693.115, built on April 6, 2021 saving the redendered styler to a file has the same result, so this isn't just an issue with jupyter.
• Tested in the console
• This issue is reproducible on two different systems, that I have tried.
• If the shape is reduced to 471 rows × 35 columns or 474 rows × 34 columns, then all rows correctly display the highlighting.
• Associated pandas bug report: 40913

Reproducible DataFrame

import pandas as pd
import numpy as np
from faker import Faker  # conda install -c conda-forge faker or pip install Faker

# for fake names
fake = Faker()

# test data
np.random.seed(365)
rows = 11000

# change 36 or 158 to test where the rows stop appearing
vals = {f'val{i}': np.random.randint(1, 11, size=(rows)) for i in range(1, 36)}
data = {'name': np.random.choice([fake.unique.name() for i in range(158)], size=rows),
        'cat': np.random.randint(1, 4, size=(rows))}
data.update(vals)

df = pd.DataFrame(data)

# used to create the mask for the background color
mean = df.groupby('cat').mean().round(2)

# calculate the mean for each name and cat
cat_mean = df.groupby(['name', 'cat']).mean()


def color(x):
    """Function to apply background color"""
    c1 = 'background-color: green'
    c = '' 
    # compare columns
    mask1 = x.gt(mean)
    # DataFrame with same index and columns names as original filled empty strings
    df1 =  pd.DataFrame(c, index=x.index, columns=x.columns)
    # modify values of df1 column by boolean mask
    df1[mask1] = c1
    display(df1)

    return df1


# Last line in notebook displays the styled dataframe
cat_mean.style.apply(color, axis=None)

# Last line in PyCharm saving rendered styler to file - comment out when in Jupyter
cm = cat_mean.style.apply(color, axis=None).set_precision(3).render()

# save the output to an html file
with open('cm_test.html', 'w') as f:
    f.write(cm)

Reference

• This answer was referenced for the function to apply the background color.
• This question is similar, but has no answer.

Output of pd.show_versions()

• All packages that were None, aren't shown to conserve space

INSTALLED VERSIONS
------------------
commit           : f2c8480af2f25efdbd803218b9d87980f416563e
python           : 3.8.8.final.0 or 3.9.2.final.0
python-bits      : 64
OS               : Windows
OS-release       : 10
Version          : 10.0.19041
machine          : AMD64
processor        : Intel64 Family 6 Model 60 Stepping 3, GenuineIntel
byteorder        : little
LOCALE           : English_United States.1252

pandas           : 1.2.3 or 1.2.4
numpy            : 1.19.2
pytz             : 2021.1
dateutil         : 2.8.1
pip              : 21.0.1
setuptools       : 52.0.0.post20210125
Cython           : 0.29.22
pytest           : 6.2.3
sphinx           : 3.5.3
xlsxwriter       : 1.3.8
lxml.etree       : 4.6.3
html5lib         : 1.1
jinja2           : 2.11.3
IPython          : 7.22.0
pandas_datareader: 0.9.0
bs4              : 4.9.3
bottleneck       : 1.3.2
fsspec           : 0.9.0
matplotlib       : 3.3.4
numexpr          : 2.7.3
openpyxl         : 3.0.7
scipy            : 1.6.2
sqlalchemy       : 1.4.5
tables           : 3.6.1
tabulate         : 0.8.9
xlrd             : 2.0.1
xlwt             : 1.3.0
numba            : 0.53.1

Workaround

Split DataFrame

• It's dissatisfying, but splitting the DataFrame and applying the style will work, since if reduces the overall size.

cat_mean.iloc[:237, :].style.apply(color, axis=None)
cat_mean.iloc[237:, :].style.apply(color, axis=None)

Save to Excel

• All rows are displayed correctly with the highlight color when saving to Excel

test = cat_mean.style.apply(color, axis=None)
test.to_excel('test.xlsx', engine='openpyxl')

Answer 1

Update

• As of pandas 1.3.0, the following implementation correctly highlights all of the expected columns and rows for the (474, 35) test data in the OP.
  • It was also successfully tested with a dataframe of shape (7760, 35).
• This implementation is from pandas Table Visualization User Guide: Set classes instead of using Styler functions

# also use code previous to list line for the test data
# calculate the mean for each name and cat
cat_mean = df.groupby(['name', 'cat']).mean()

def test(s, props=''):
    t = np.where(s.gt(mean[s.name]), props, '')
    return t


build = lambda x: pd.DataFrame(x, index=cat_mean.index, columns=cat_mean.columns)
cls1 = build(cat_mean.apply(test, props='cls-1 ', axis=0))

test = cat_mean.style.set_table_styles([{'selector': '.cls-1', 'props': [('color', 'white'), ('background-color', 'darkblue')]}]).set_td_classes(cls1)

# save the output to an html file
with open('cm_test.html', 'w') as f:
    f.write(test.render())

• Output of working implementation
• Output of implementation in OP

Answering: Why doesn't this work in Chrome or Edge?

• Per bug #39400, the issue occurs for large DataFrames because Styler puts all CSS ids on a single attribute, which are not resolved be all browsers.
• In the following small snippet, see that all the ids are at the top.
  • The snippet ids are for 5 rows and 35 columns, though only data for 1 table row is included.

<style  type="text/css" >
#T__row0_col0,#T__row0_col1,#T__row0_col4,#T__row0_col5,#T__row0_col6,#T__row0_col11,#T__row0_col12,#T__row0_col13,#T__row0_col16,#T__row0_col19,#T__row0_col20,#T__row0_col22,#T__row0_col23,#T__row0_col24,#T__row0_col26,#T__row0_col27,#T__row0_col28,#T__row0_col30,#T__row0_col33,#T__row0_col34,#T__row1_col0,#T__row1_col1,#T__row1_col4,#T__row1_col8,#T__row1_col9,#T__row1_col11,#T__row1_col13,#T__row1_col15,#T__row1_col17,#T__row1_col21,#T__row1_col22,#T__row1_col26,#T__row1_col31,#T__row1_col34,#T__row2_col0,#T__row2_col1,#T__row2_col3,#T__row2_col7,#T__row2_col8,#T__row2_col9,#T__row2_col10,#T__row2_col12,#T__row2_col13,#T__row2_col16,#T__row2_col19,#T__row2_col20,#T__row2_col24,#T__row2_col26,#T__row2_col27,#T__row2_col28,#T__row2_col30,#T__row2_col32,#T__row3_col0,#T__row3_col3,#T__row3_col4,#T__row3_col6,#T__row3_col7,#T__row3_col8,#T__row3_col9,#T__row3_col15,#T__row3_col17,#T__row3_col20,#T__row3_col22,#T__row3_col27,#T__row3_col28,#T__row3_col29,#T__row3_col31,#T__row3_col34,#T__row4_col0,#T__row4_col1,#T__row4_col2,#T__row4_col3,#T__row4_col4,#T__row4_col6,#T__row4_col8,#T__row4_col14,#T__row4_col16,#T__row4_col17,#T__row4_col18,#T__row4_col19,#T__row4_col22,#T__row4_col23,#T__row4_col25,#T__row4_col27,#T__row4_col29,#T__row4_col32,#T__row4_col33{
            text-align:  center;
        }#T__row0_col2,#T__row0_col3,#T__row0_col7,#T__row0_col8,#T__row0_col9,#T__row0_col10,#T__row0_col14,#T__row0_col15,#T__row0_col17,#T__row0_col18,#T__row0_col21,#T__row0_col25,#T__row0_col29,#T__row0_col31,#T__row0_col32,#T__row1_col2,#T__row1_col3,#T__row1_col5,#T__row1_col6,#T__row1_col7,#T__row1_col10,#T__row1_col12,#T__row1_col14,#T__row1_col16,#T__row1_col18,#T__row1_col19,#T__row1_col20,#T__row1_col23,#T__row1_col24,#T__row1_col25,#T__row1_col27,#T__row1_col28,#T__row1_col29,#T__row1_col30,#T__row1_col32,#T__row1_col33,#T__row2_col2,#T__row2_col4,#T__row2_col5,#T__row2_col6,#T__row2_col11,#T__row2_col14,#T__row2_col15,#T__row2_col17,#T__row2_col18,#T__row2_col21,#T__row2_col22,#T__row2_col23,#T__row2_col25,#T__row2_col29,#T__row2_col31,#T__row2_col33,#T__row2_col34,#T__row3_col1,#T__row3_col2,#T__row3_col5,#T__row3_col10,#T__row3_col11,#T__row3_col12,#T__row3_col13,#T__row3_col14,#T__row3_col16,#T__row3_col18,#T__row3_col19,#T__row3_col21,#T__row3_col23,#T__row3_col24,#T__row3_col25,#T__row3_col26,#T__row3_col30,#T__row3_col32,#T__row3_col33,#T__row4_col5,#T__row4_col7,#T__row4_col9,#T__row4_col10,#T__row4_col11,#T__row4_col12,#T__row4_col13,#T__row4_col15,#T__row4_col20,#T__row4_col21,#T__row4_col24,#T__row4_col26,#T__row4_col28,#T__row4_col30,#T__row4_col31,#T__row4_col34{
            background-color:  green;
            text-align:  center;
        }</style><table id="T__" ><thead>    <tr>        <th class="blank" ></th>        <th class="blank level0" ></th>        <th class="col_heading level0 col0" >val1</th>        <th class="col_heading level0 col1" >val2</th>        <th class="col_heading level0 col2" >val3</th>        <th class="col_heading level0 col3" >val4</th>        <th class="col_heading level0 col4" >val5</th>        <th class="col_heading level0 col5" >val6</th>        <th class="col_heading level0 col6" >val7</th>        <th class="col_heading level0 col7" >val8</th>        <th class="col_heading level0 col8" >val9</th>        <th class="col_heading level0 col9" >val10</th>        <th class="col_heading level0 col10" >val11</th>        <th class="col_heading level0 col11" >val12</th>        <th class="col_heading level0 col12" >val13</th>        <th class="col_heading level0 col13" >val14</th>        <th class="col_heading level0 col14" >val15</th>        <th class="col_heading level0 col15" >val16</th>        <th class="col_heading level0 col16" >val17</th>        <th class="col_heading level0 col17" >val18</th>        <th class="col_heading level0 col18" >val19</th>        <th class="col_heading level0 col19" >val20</th>        <th class="col_heading level0 col20" >val21</th>        <th class="col_heading level0 col21" >val22</th>        <th class="col_heading level0 col22" >val23</th>        <th class="col_heading level0 col23" >val24</th>        <th class="col_heading level0 col24" >val25</th>        <th class="col_heading level0 col25" >val26</th>        <th class="col_heading level0 col26" >val27</th>        <th class="col_heading level0 col27" >val28</th>        <th class="col_heading level0 col28" >val29</th>        <th class="col_heading level0 col29" >val30</th>        <th class="col_heading level0 col30" >val31</th>        <th class="col_heading level0 col31" >val32</th>        <th class="col_heading level0 col32" >val33</th>        <th class="col_heading level0 col33" >val34</th>        <th class="col_heading level0 col34" >val35</th>    </tr>    <tr>        <th class="index_name level0" >name</th>        <th class="index_name level1" >cat</th>        <th class="blank" ></th>        <th class="blank" ></th>        <th class="blank" ></th>        <th class="blank" ></th>        <th class="blank" ></th>        <th class="blank" ></th>        <th class="blank" ></th>        <th class="blank" ></th>        <th class="blank" ></th>        <th class="blank" ></th>        <th class="blank" ></th>        <th class="blank" ></th>        <th class="blank" ></th>        <th class="blank" ></th>        <th class="blank" ></th>        <th class="blank" ></th>        <th class="blank" ></th>        <th class="blank" ></th>        <th class="blank" ></th>        <th class="blank" ></th>        <th class="blank" ></th>        <th class="blank" ></th>        <th class="blank" ></th>        <th class="blank" ></th>        <th class="blank" ></th>        <th class="blank" ></th>        <th class="blank" ></th>        <th class="blank" ></th>        <th class="blank" ></th>        <th class="blank" ></th>        <th class="blank" ></th>        <th class="blank" ></th>        <th class="blank" ></th>        <th class="blank" ></th>        <th class="blank" ></th>    </tr></thead><tbody>
                <tr>
                        <th id="T__level0_row0" class="row_heading level0 row0" rowspan="3">Alisha Ortiz</th>
                        <th id="T__level1_row0" class="row_heading level1 row0" >1</th>
                        <td id="T__row0_col0" class="data row0 col0" >4.46</td>
                        <td id="T__row0_col1" class="data row0 col1" >4.62</td>
                        <td id="T__row0_col2" class="data row0 col2" >5.73</td>
                        <td id="T__row0_col3" class="data row0 col3" >6.12</td>
                        <td id="T__row0_col4" class="data row0 col4" >4.77</td>
                        <td id="T__row0_col5" class="data row0 col5" >4.73</td>
                        <td id="T__row0_col6" class="data row0 col6" >4.50</td>
                        <td id="T__row0_col7" class="data row0 col7" >6.12</td>
                        <td id="T__row0_col8" class="data row0 col8" >5.50</td>
                        <td id="T__row0_col9" class="data row0 col9" >5.92</td>
                        <td id="T__row0_col10" class="data row0 col10" >6.08</td>
                        <td id="T__row0_col11" class="data row0 col11" >4.92</td>
                        <td id="T__row0_col12" class="data row0 col12" >5.42</td>
                        <td id="T__row0_col13" class="data row0 col13" >5.38</td>
                        <td id="T__row0_col14" class="data row0 col14" >6.08</td>
                        <td id="T__row0_col15" class="data row0 col15" >5.77</td>
                        <td id="T__row0_col16" class="data row0 col16" >5.31</td>
                        <td id="T__row0_col17" class="data row0 col17" >5.58</td>
                        <td id="T__row0_col18" class="data row0 col18" >6.12</td>
                        <td id="T__row0_col19" class="data row0 col19" >4.77</td>
                        <td id="T__row0_col20" class="data row0 col20" >5.19</td>
                        <td id="T__row0_col21" class="data row0 col21" >5.96</td>
                        <td id="T__row0_col22" class="data row0 col22" >4.88</td>
                        <td id="T__row0_col23" class="data row0 col2