Python Pandas - highlighting cells in a dataframe

Question

I would like to test if the values of a column are bigger than another specific value of the same data frame. If a value is bigger, I want to highlight this specific cell.

I tried this:

import pandas as pd

b = pd.DataFrame([[5,7,3],[2,3,4],[8,4,7]])

for i in range(0, len(b)):
    for j in range(0, len(b.columns)):
        if  b.iloc[i][j] >  b.iloc[2][j]:
            b.style.applymap(lambda  x: 'background-color : blue' if b.iloc[i][j] >  b.iloc[2][j] else '') 

b

So in this example I want to check if 5 or 7 is bigger than 3 (column 1), 2 or 3 bigger than 4 (column 2) and 8 or 4 is bigger than 7.

It doesn't color anything... I hope someone can help me. Thx in advance.

Does this answer your question? Conditionally format Python pandas cell — Shir
– Shir, Commented Mar 15, 2021 at 11:08
I've seen this question already… it basically the code is the same but in my case it is not working... — SeaSeaEss
– SeaSeaEss, Commented Mar 15, 2021 at 11:46
Interesting.. Can you add a minimal runnable snippet of your code? — Shir
– Shir, Commented Mar 15, 2021 at 11:50
Sorry I had some Problems entering code down here. It's now in the main Question. — SeaSeaEss
– SeaSeaEss, Commented Mar 15, 2021 at 12:06
I added a solution that works for me directly in a jupyter notebook. — Shir
– Shir, Commented Mar 15, 2021 at 12:44

Shir · Accepted Answer · 2021-03-15 12:48:33Z

2

Try this solution:

import pandas as pd
import numpy as np

df = pd.DataFrame([[5,7,8],[2,3,4],[8,4,9]])

def highlight(s):
    '''
    highlight the maximum in a Series.
    '''
    is_max = s >= s[2]
    return ['background-color: blue' if v else '' for v in is_max]

df.style.apply(highlight, axis=0)

Note that the solution is based on the thread we discussed. The main change is the condition inside the highlight function. Using applymap works on a single cell each time, and has no access to its location in the dataframe. Using apply works on a single row each time and enables comparing to cell in the same row and different column.

edited Mar 15, 2021 at 12:48

answered Mar 15, 2021 at 12:34

Shir

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8 Comments

SeaSeaEss Over a year ago

But I don't want to highlight the maximum of each row. I want to highlight in a huge data frame column by column the values which are bigger than the last value in this column. And changing applymap tp apply doen't work either..

Shir Over a year ago

Sorry for misunderstanding. I changed the axis in the last line of code from 1 to 0. This makes it work on columns rather than rows.

SeaSeaEss Over a year ago

Now it Looks good! Hopefully I can adapt this to my data frame and use it in the loops.. Tank you!

Shir Over a year ago

You don't need loops to run it, it implicitly contains them inside. Working with for loops on data frames, especially when they are large is usually a bad practice. Let me know if you have more questions.

SeaSeaEss Over a year ago

Ooh you're true. Okay now I need to mark values bigger then last value of the column and smaller then second last value of the column and this column by column. I guess I Need a loop to automatically do this for every column?

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