Styling the background color of pandas index cell

Question

I want to change the background styling color of the pandas table.

Example:

df = pd.DataFrame({
'group': ['A','B','C','D'],
'var1': [38, 1.5, 30, 4],
'var2': [29, 10, 9, 34],
'var3': [8, 39, 23, 24],
'var4': [7, 31, 33, 14],
'var5': [28, 15, 32, 14]
})

df.set_index('group', inplace=True)

I want the background color of the index cell (and just the index cell) A,C in blue and B,D in red.

I looked at the styling documentation but I could not find an example that matches this case.

Answer 1

Based on the limitations of df.style, coloring index and columns is not implemented.

If you are okay to color the values based on the index, you can do something like this. Create a dictionary and apply the color based on the index using index.map

c1 = 'background-color: blue'
c2 = 'background-color: red'
d = {"A":c1,"B":c2,"C":c1,"D":c2}

df.style.apply(lambda x: x.index.map(d))

---

Answer 2

This feature is not currently available and the next release for this might be December 2021 (https://github.com/pandas-dev/pandas/pull/41893). However, you can easily work around this by using table styles. See my answer below:

df = pd.DataFrame([[1,2],[3,4],[5,6],[7,8]], index=["A", "B", "C", "D"])
green = [{'selector': 'th', 'props': 'background-color: green'}]
red = [{'selector': 'th', 'props': 'background-color: red'}]
df.style.set_table_styles({"A": green, "B": red, "C": green, "D": red}, axis=1)