Alternate row colour for dataframe - pandas

Question

Trying to build on from this: Python: Color pandas dataframe based on MultiIndex
I've extended the code:
import pandas as pd
i = pd.MultiIndex.from_tuples([(0, 'zero'), (0, 'one'), (1, 'zero'), (1, 'one'), (1, 'two'), (1, 'three'), (1, 'four'), (2, 'zero'), (2, 'one'), (2, 'two'), (2, 'three'), (2, 'four')], names=['level_0', 'level_1'])
df = pd.DataFrame(range(0, len(i)), index=i, columns=['foo'])
colors = {0: (0.6, 0.8, 0.8, 1), 1: (1, 0.9, 0.4, 1), 2: (0.6, 0.8, 0.8, 1)}
#convert rgba to integers
c1 = {k: (int(r * 255),int(g * 255),int(b * 255), a) for k, (r,g,b,a) in colors.items()}
c2 = {k: (int(r * 255),int(g * 255),int(b * 255), 0.25) for k, (r,g,b,a) in colors.items()}
#get values of first level of MulitIndex
idx = df.index.get_level_values(0)
#counter per first level for pair and unpair coloring
zipped = zip(df.groupby(idx).cumcount(), enumerate(idx))
css = [{'selector': f'.row{i}', 'props': [('background-color', f'rgba{c1[j]}')]}
if v % 2 == 0
else {'selector': f'.row{i}', 'props': [('background-color', f'rgba{c2[j]}')]}
for v,(i, j) in zipped]
df1.style.set_table_styles(css)
And got this:
It seems tedious to do this manually. So how do I go about generalising it so that it covers all rows, and the pattern applies even if I apply it to other such 2-level multi-index dataframes?

Answer 1

Here is one way to do it with cycle from Python standard library's itertools module:
import pandas as pd
# Setup
i = pd.MultiIndex.from_tuples(
[
(0, "zero"),
(0, "one"),
(1, "zero"),
(1, "one"),
(1, "two"),
(1, "three"),
(1, "four"),
(2, "zero"),
(2, "one"),
(2, "two"),
(2, "three"),
(2, "four"),
(3, "one"),
],
names=["level_0", "level_1"],
)
df = pd.DataFrame(range(0, len(i)), index=i, columns=["foo"])
# Define two pairs of colors (dark and light green/yellow)
from itertools import cycle
colors = [(0.6, 0.8, 0.8), (1, 0.9, 0.4)] # green, yellow
color_cycle = cycle(
[
{
k: (int(c[0] * 255), int(c[1] * 255), int(c[2] * 255), a)
for k, a in enumerate([1, 0.25])
}
for c in colors
]
)
# Define color for each row
bg_colors = []
for i in df.index.get_level_values(0).unique():
color = next(color_cycle)
row_color = cycle(
[
{
"props": [("background-color", f"rgba{color[0]}")],
},
{
"props": [("background-color", f"rgba{color[1]}")],
},
]
)
for _ in range(df.loc[(i,), :].shape[0]):
bg_colors.append(next(row_color))
# Style dataframe
css = [{"selector": f".row{i}"} | color for i, color in enumerate(bg_colors)]
df.style.set_table_styles(css)
Output from last cell in Jupyter notebook: