Pandas group by specific column and aggregation min, max, mean, first

 import pandas as pd

# Setup
df = pd.DataFrame([
    {
        "item":"truck",
        "color":"red"
    },
    {
        "item":"truck",
        "color":"red"
    },
    {
        "item":"car",
        "color":"black"
    },
    {
        "item":"truck",
        "color":"blue"
    },
    {
        "item":"car",
        "color":"black"
    }
])

df_grouped = df.groupby(["item", "color"]).agg(
    count_col=pd.NamedAgg(column="color", aggfunc="count")
)
print(df_grouped)

from : https://stackoverflow.com/questions/29836477/pandas-create-new-column-with-count-from-groupby