Pandas: Add an empty row after every index in a MultiIndex dataframe

Use custom function for add empty rows in GroupBy.apply:

def f(x):
    x.loc[('', ''), :] = ''
    return x

Or:

def f(x):
    return x.append(pd.DataFrame('', columns=df.columns, index=[(x.name, '')]))

---

df = df.groupby(level=0, group_keys=False).apply(f)
print (df)
             IA1 IA2 IA3
Name Subject            
Abc  DS       45  43  34
     DMS      43  23  45
     ADA      32  46  36
                        
Bcd  BA       45  35  37
     EAD      23  45  12
     DS       23  35  43
                        
Cdf  EAD      34  33  23
     ADA      12  34  25
                        

Adding another way using df.reindex and fill_value as '' after using pd.MultiIndex.from_product and Index.union and then sorting it.

idx = df.index.union(pd.MultiIndex.from_product((df.index.levels[0],[''])),sort=False)
out = df.reindex(sorted(idx,key=lambda x: x[0]),fill_value='')

---

print(out)

             IA1 IA2 IA3
Name Subject            
Abc  DS       45  43  34
     DMS      43  23  45
     ADA      32  46  36
                        
Bcd  BA       45  35  37
     EAD      23  45  12
     DS       23  35  43
                        
Cdf  EAD      34  33  23
     ADA      12  34  25
 

---

We use sort=False when using Index.union the index so order is retained , then using sorted on the first element returns:

sorted(idx,key=lambda x:x[0])

[('Abc', 'DS'),
 ('Abc', 'DMS'),
 ('Abc', 'ADA'),
 ('Abc', ''),
 ('Bcd', 'BA'),
 ('Bcd', 'EAD'),
 ('Bcd', 'DS'),
 ('Bcd', ''),
 ('Cdf', 'EAD'),
 ('Cdf', 'ADA'),
 ('Cdf', '')]

# reset index 
dfn = df.reset_index()
# find the border idx of 'Name', [2, 5, 7]
idx_list = dfn.drop_duplicates('Name', keep='last').index
# use the border idx, create an empty df, and append to the origin df, then sort the index
df_append = pd.DataFrame('', index = idx_list, columns = dfn.columns)
obj = dfn.append(df_append).sort_index().set_index(['Name', 'Subject'])
print(obj)

             IA1 IA2 IA3
Name Subject            
Abc  DS       45  43  34
     DMS      43  23  45
     ADA      32  46  36
                        
Bcd  BA       45  35  37
     EAD      23  45  12
     DS       23  35  43
                        
Cdf  EAD      34  33  23
     ADA      12  34  25