Styling Pandas Columns

Question

I am working on a dataframe df. I am trying to set the background color of the cells of the ‘SupTrend’ column. The background should be red when the value in ‘Price’ column is lower than the value in ‘SupTrend’ column, and it should be green otherwise. I tried everything, checked the documentation and I can’t find any explanation or solution for my problem. It seems data inside the function is converted to string and I guess I can’t convert it to float. Does someone knows how to solve this?


    def highlight_suptrend(x, data):
           return f"background-color: red;" if data['Price'].all() < data['SupTrend'].all() else f"background-color: green;"
    
    df.style.applymap(highlight_suptrend, data=df[['Price', 'SupTrend']], subset=['SupTrend'])

Here is the result:

Asked By: Luis Rito Filipe

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Source

Answer 1

You want to use style.apply rather than style.applymap, and then use np.where for your function return, selecting red where Price is lower than SupTrend and green otherwise (using: Series.lt).

import pandas as pd
import numpy as np

# some mock data
np.random.seed(1)

data = {'Price': np.random.randint(1,11,10),
        'SupTrend': np.random.randint(1,11,10)}

df = pd.DataFrame(data)

def highlight_suptrend(x, data):
    return np.where(data['Price'].lt(data['SupTrend']), 
                    "background-color: red", 
                    "background-color: green")

df.style.apply(highlight_suptrend, 
               data=df[['Price', 'SupTrend']], 
               subset=['SupTrend'])

Result:

Answered By: ouroboros1

Styling Pandas Columns

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