I'm using this code to get to this dataframe:

df=df[['rank','Grade','search']].groupby(['Grade','rank']).count()
df2=df.div(df.groupby(['Grade']).transform('sum'))
df3=df2.unstack()

| search   | 
| rank     |  1  |  2  |  3  |  4  |  5  | 5-10 | 10-20 | 20  |
| Grade ---|-----|-----|-----|-----|-----|------|-------|-----|                         
| A        | 0.2 | 0.2 | 0.2 | 0.1 | 0.04| 0.04 | 0.01  | NaN |
| B        | 0.3 | 0.2 | 0.1 | 0.2 | 0.03| 0.05 | 0.2   | NaN |

Now, to plot a barplot for Grade, I would normally do reset_index() on the unstacked table. However if I do it now I get this error:

TypeError: cannot insert an item into a CategoricalIndex that is not already an existing category

I have tried all sorts of things and I can't fix it. It's strange because it works for another table with the same exact format only opposite (i.e grouped by rank first and then grade)

CodePudding user response：

You can convert categorical to strings:

df3 = df_grade2.unstack().rename(columns=str).reset_index()