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). How can I achieve that in pandas using the HTML formatter?
A typical use case is highlighting significant values in a table. For example:
correlation p-value
0 0.5 0.1
1 0.1 0.8
2 0.9 *0.01*
pandas allows to define custom formatters for HTML output – to obtain above output one could use:
import pandas as pd
from pandas.core import format
from StringIO import StringIO
buf = StringIO()
df = pd.DataFrame({'correlation':[0.5, 0.1,0.9], 'p_value':[0.1,0.8,0.01]})
fmt = format.DataFrameFormatter(df,
formatters={'p_value':lambda x: "*%f*" % x if x<0.05 else str(x)})
format.HTMLFormatter(fmt).write_result(buf)
However, I would like to change the style for significant values (for example, by using bold font).
A possible solution would be to attach a CSS class to <td>
tags in the HTML output, which could be then formatted using CSS stylesheet. The above would then become:
<table border="1" class="dataframe">
<thead>
<tr style="text-align: right;">
<th></th>
<th>correlation</th>
<th>p_value</th>
</tr>
</thead>
<tbody>
<tr>
<td>0</td>
<td> 0.5</td>
<td> 0.10</td>
</tr>
<tr>
<td>1</td>
<td> 0.1</td>
<td> 0.80</td>
</tr>
<tr>
<td>2</td>
<td> 0.9</td>
<td class='significant'> 0.01</td>
</tr>
</tbody>
</table>
Edit: As suggested by @Andy-Hayden I can add formatting by simply replacing stars with <span class="signifcant">...</span>
in my example:
import pandas as pd
from StringIO import StringIO
buf = StringIO()
significant = lambda x: '<span class="significant">%f</span>' % x if x<0.05 else str(x)
df = pd.DataFrame({'correlation':[0.5, 0.1,0.9], 'p_value':[0.1,0.8,0.01]})
df.to_html(buf, formatters={'p_value': significant})
Newer versions of pandas escape the tags. To avoid it replace last line with:
df.to_html(buf, formatters={'p_value': significant}, escape=False)
Answers:
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.
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>
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). How can I achieve that in pandas using the HTML formatter?
A typical use case is highlighting significant values in a table. For example:
correlation p-value
0 0.5 0.1
1 0.1 0.8
2 0.9 *0.01*
pandas allows to define custom formatters for HTML output – to obtain above output one could use:
import pandas as pd
from pandas.core import format
from StringIO import StringIO
buf = StringIO()
df = pd.DataFrame({'correlation':[0.5, 0.1,0.9], 'p_value':[0.1,0.8,0.01]})
fmt = format.DataFrameFormatter(df,
formatters={'p_value':lambda x: "*%f*" % x if x<0.05 else str(x)})
format.HTMLFormatter(fmt).write_result(buf)
However, I would like to change the style for significant values (for example, by using bold font).
A possible solution would be to attach a CSS class to <td>
tags in the HTML output, which could be then formatted using CSS stylesheet. The above would then become:
<table border="1" class="dataframe">
<thead>
<tr style="text-align: right;">
<th></th>
<th>correlation</th>
<th>p_value</th>
</tr>
</thead>
<tbody>
<tr>
<td>0</td>
<td> 0.5</td>
<td> 0.10</td>
</tr>
<tr>
<td>1</td>
<td> 0.1</td>
<td> 0.80</td>
</tr>
<tr>
<td>2</td>
<td> 0.9</td>
<td class='significant'> 0.01</td>
</tr>
</tbody>
</table>
Edit: As suggested by @Andy-Hayden I can add formatting by simply replacing stars with <span class="signifcant">...</span>
in my example:
import pandas as pd
from StringIO import StringIO
buf = StringIO()
significant = lambda x: '<span class="significant">%f</span>' % x if x<0.05 else str(x)
df = pd.DataFrame({'correlation':[0.5, 0.1,0.9], 'p_value':[0.1,0.8,0.01]})
df.to_html(buf, formatters={'p_value': significant})
Newer versions of pandas escape the tags. To avoid it replace last line with:
df.to_html(buf, formatters={'p_value': significant}, escape=False)
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.
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>