Grouping Pandas dataframe across rows - 2.0

Question

Further to this question Grouping Pandas dataframe across rows, the op is:

          amount
clients           
Comp1    16.360417
Comp2    69.697501
Comp3    85.700000
Comp4    36.666667
Comp5    44.156500 

If a date column is added to the input:

tdate,client1,client2,client3,client4,client5,client6,amount
12/31/2017,,,Comp1,,,4.475000
12/31/2017,,,Comp2,,,16.305584
10/31/2107,,,Comp3,,,4.050000
10/31/2017,Comp2,Comp1,,Comp4,,,21.000000
1/1/2017,,,Comp4,,,30.000000
2/2/2017,Comp1,,Comp2,,,5.137500
10/31/2017,,,Comp3,,,52.650000
12/31/2017,,,Comp1,,,2.650000
10/31/2017,Comp3,,,Comp3,,,29.000000
12/31/2017,Comp5,,,Comp2,,,20.809000
1/1/2017,Comp5,,,Comp2,,,15.100000
10/31/2017,Comp5,,,Comp2,,,52.404000

How would we get this output:

12/31/2017 Comp1 4.475+2.65
12/31/2017 Comp2 16.305584+20.809/2 
10/31/2017 Comp2 21/3+5.1375/2+52.404/2
1/1/2017   Comp2 15.1/2
10/31/2017 Comp3 4.05+52.65+29
1/1/2017   Comp4 30
10/21/2017 Comp4 21/3
12/31/2017 Comp5 20.809/2
1/1/2017   Comp5 15.1/2
10/31/2017 Comp5 52.404/2   

Answer 1

Improving from previous answer, we need to use stack by setting two columns as index.

cols= ['amount','tdate']
df['new'] = df['amount']/df.drop(cols,1).count(1)

#Set the index as new and tdate by droping amount column, stack and drop the nans.
x = df.drop(['amount'],1).set_index(['new','tdate']).stack().dropna()

#Create dataframe from amount,tdate and the clients
ndf = pd.DataFrame({'amount':x.index.get_level_values('new'),'tdate':x.index.get_level_values('tdate'),'clients':x.values})

#Groupby `clients` and `tdate` 
ndf.groupby(['clients','tdate']).sum().reset_index()

Output :

  clients       tdate     amount
0    Comp1  10/31/2017   7.000000
1    Comp1  12/31/2017   7.125000
2    Comp1    2/2/2017   2.568750
3    Comp2    1/1/2017   7.550000
4    Comp2  10/31/2017  33.202000
5    Comp2  12/31/2017  26.710084
6    Comp2    2/2/2017   2.568750
7    Comp3  10/31/2017  81.650000
8    Comp3  10/31/2107   4.050000
9    Comp4    1/1/2017  30.000000
10   Comp4  10/31/2017   7.000000
11   Comp5    1/1/2017   7.550000
12   Comp5  10/31/2017  26.202000
13   Comp5  12/31/2017  10.404500