I have a problem. I have articles and these articles have a unique `id`. The problem is, however, the `article` description aka `article` - this is not unique.
I would like to try changing the name of the `article` description `article` so that there is only one description left. I always want to use the `article` name that occurs most often.

I have tried something, however I don't know how to access that with `.apply(lambda x: ...` and write the most used item out to me and then set that as the name.

How can I change the description of the article so that only the most frequently mentioned article description is included?

```py
    id  article            cost
0   1   Bendge             15.30
1   1   Bendge             15.30
2   1   Bendge V2          15.30
3   1   Bendge - volumne 2 15.30
4   5   SEF                14.89
5   1   Bendge             15.30
6   2   DFH                 4.56
7   2   DFH                 4.56
8   2   DFH V2              4.56
9   2   DFH - volumne 2     4.56
10  2   DFH                 4.56

```

Code

```py
d = {'id': [1, 1, 1, 1, 5, 1, 2, 2, 2, 2, 2],
     'article': ['Bendge', 'Bendge', 'Bendge V2', 'Bendge - volumne 2', 'SEF', 'Bendge',
                 'DFH', 'DFH', 'DFH V2', 'DFH - volumne 2', 'DFH'],
     'cost': [15.30, 15.30, 15.30, 15.30, 14.89, 15.30,
              4.56, 4.56, 4.56, 4.56, 4.56],
    }
df = pd.DataFrame(data=d)
display(df)

df.loc[df['id'] == 1, ['id','article']].value_counts().head(1)
[OUT]
id  article
1   Bendge     3
dtype: int64

df['article'] = df.apply(lambda x: x[['id','article']].value_counts().head(1))
[OUT]
KeyError: "None of [Index(['id', 'article'], dtype='object')] are in the [index]"

```

What I want

```py
    id  article cost
0   1   Bendge  15.30
1   1   Bendge  15.30
2   1   Bendge  15.30
3   1   Bendge  15.30
4   5   SEF     14.89
5   1   Bendge  15.30
6   2   DFH      4.56
7   2   DFH      4.56
8   2   DFH      4.56
9   2   DFH      4.56
10  2   DFH      4.56

```