Adding a value at the end of a column in a multindex column dataframe-CodePudding

I have a simple problem that probably has a simple solution but I couldn't found it anywhere. I have the following multindex column Dataframe:

mux = pd.MultiIndex.from_product(['A','B','C'], ['Datetime', 'Str', 'Ret']])
dfr = pd.DataFrame(columns=mux)

  |      A         |        B       |        C       |
  |Datetime|Str|Ret|Datetime|Str|Ret|Datetime|Str|Ret|

I need to add values one by one at the end of a specific subcolumn. For example add one value at the end of column A sub-column Datetime and leave the rest of the row as it is, then add another value to column B sub-column Str and again leave the rest of the values in the same row untouched and so on. So my questions are: Is it possible to target individual locations in this type of Dataframes? How? and also Is it possible to append not a full row but an individual value always at the end after the previous value without knowing where the end is?. Thank you so much for your answers.

CodePudding user response：

IIUC, you can use .loc:

idx = len(dfr)  # get the index of the next row after the last one
dfr.loc[idx, ('A', 'Datetime')] = pd.to_datetime('2021-09-24')
dfr.loc[idx, ('B', 'Str')] = 'Hello'
dfr.loc[idx, ('C', 'Ret')] = 4.3

Output:

>>> dfr
                     A                  B                    C          
              Datetime  Str  Ret Datetime    Str  Ret Datetime  Str  Ret
0  2021-09-24 00:00:00  NaN  NaN      NaN  Hello  NaN      NaN  NaN  4.3