I would like to ask you how to count the frequency of each Pandas group.

>>> df = pd.DataFrame({"category":["A", "A", "B"], "content":["apple, orange", "banana, apple, melon", "peach, apple, orange" ]})
>>> df
  category               content
0        A         apple, orange
1        A  banana, apple, melon
2        B  peach, apple, orange
>>> df["content"] = df["content"].str.split(", ")
>>> df
  category                 content
0        A         [apple, orange]
1        A  [banana, apple, melon]
2        B  [peach, apple, orange]
>>> df["content"] = df["content"].apply(set)
>>> df
  category                 content
0        A         {orange, apple}
1        A  {melon, banana, apple}
2        B  {peach, orange, apple}
>>> df.groupby("category").apply(lambda x: set.union(*x.content))
category
A    {melon, banana, orange, apple}
B            {peach, orange, apple}
dtype: object
>>> group_df = df.groupby("category").apply(lambda x: set.union(*x.content))
>>> for tup in group_df.to_frame().itertuples():
    tup1_str = ", ".join(sorted(tup[1]))
    n = len(tup[1])
    print(f"{tup[0]}: {tup1_str} ({n} pieces)")


A: apple, banana, melon, orange (4 pieces)
B: apple, orange, peach (3 pieces)