Pandas – Style – Background Gradient using other dataframe

Question

I like using the background_gradient as it helps me look at my dataframes in an excel way.
But I’m wondering if I there is a way I could map the colors to the figures in another dataframe.
For example, something I am keen to do is to color the dataframe using a dataframe of zscores so i can see quickly the value of outliers.

A = pd.DataFrame(np.random.randn(6, 3), columns=['a', 'b', 'c']) 
B = pd.DataFrame(np.random.randn(6, 3), columns=['a', 'b', 'c'])
A.style.background_gradient(???)

I’m wondering how to use background_gradient so that it uses the values in the dataframe B to style A.

Asked By: Tanguy Bretagne

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Source

Answer 1

I don’t see a different method other than altering the background_gradient code for transferring style from one dataframe to other i.e

import pandas as pd
import matplotlib.pyplot as plt  
from matplotlib import colors

def b_g(s, cmap='PuBu', low=0, high=0):
    # Pass the columns from Dataframe A 
    a = A.loc[:,s.name].copy()
    rng = a.max() - a.min()
    norm = colors.Normalize(a.min() - (rng * low),
                        a.max() + (rng * high))
    normed = norm(a.values)
    c = [colors.rgb2hex(x) for x in plt.cm.get_cmap(cmap)(normed)]
    return ['background-color: %s' % color for color in c]

B.style.apply(b_g,cmap='PuBu')

Output :

Hope it helps

Answered By: Bharath

Pandas – Style – Background Gradient using other dataframe

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