ENH: allow ranges to be set on Styler .bar()

[psychemedia]

When generating in table bar charts using the Styler .bar():

• extreme outliers in a column mask differences in other values;
• comparisons across columns are not supported.

One solution would be to allow the setting of explicit bounds on the range of values used to limit the bar extrema using explicit values rather than s.min() and s.max().

Cell values exceeding the range limits could be extending to the cell edge / maximum limit value and then coloured with an "overflow" colour.

[WillAyd]

Please be sure to checkout out the contributing guide on how to open bug reports:

https://pandas.pydata.org/pandas-docs/stable/contributing.html#bug-reports-and-enhancement-requests

This is missing version information and a minimally reproducible example. You can find more information on how to construct one of those here:

http://matthewrocklin.com/blog/work/2018/02/28/minimal-bug-reports

It's difficult to infer from what you have here alone exactly what the problem is and what you are looking for, so try going through the above to see if we can get to something more explicit

[psychemedia]

Pandas version 0.23.0

In the following example a dataframe is created with a column containing two outlier values (x1) and two columns where it would be useful to depict and compare the values over the same range even though in this example the ranges differ:

import pandas as pd
import numpy as np

df=pd.DataFrame({'x1':list(np.random.randint(-10,10,size=10))+[-500,1000, -1000],
               'y1':list(np.random.randint(-5,5,size=13)), 'y2':list(np.random.randint(-2,3,size=13)) })

df.style.bar( align='zero', color=[ '#5fba7d','#d65f5f'])

In column x1, the outlier values set the max/min range values used to display the styled bar and the variation in the non-outlier values is masked. It would be useful to be able to set max / min limits to so that variation in the non-outlier values can be depicted. For example, setting min,max=(-10,10) and then colouring squares with outlier values [-500,1000, -1000] differently to show they are outside the depicted range.

For columns y1 and y2, it may be desired to display the bars over the same range, for example min,max=(-5,5) so that a direct visual comparison can be made across columns y1 and y2.

[soxofaan]

FYI: pull request #21548 now includes support for vmin and vmax arguments in Styler.bar