Running subtraction calculation
Question:
I have this dataframe and I want to achieve this type of running subtraction calculation:
For ID 1 at index 1, the payment of 10 must be subtracted from the amount of 1000 and result of 990 placed in balance field.
For ID 1 at index 2, the payment of 15 must be subtracted from the 990 and result placed in balance which in this case was 975.
For ID 1 at index 3, the payment of 20 must be subtracted from the 975 and result placed in balance which in this case was 955.
For ID 2 at index 1, the payment of 5 must be subtracted from the amount of 200 and result of 195 placed in balance field.
For ID 2 at index 2, the payment of 5 must be subtracted from the 195 and result of 190 placed in balance field.
Answers:
df['bal']=df['amount']-df.groupby('ID')['payment'].transform('cumsum')
df
ID payment amount balance bal
0 1 10 1000 990 990
1 1 15 1000 975 975
2 1 20 1000 955 955
3 2 5 200 195 195
4 2 5 200 190 190
I have this dataframe and I want to achieve this type of running subtraction calculation:
For ID 1 at index 1, the payment of 10 must be subtracted from the amount of 1000 and result of 990 placed in balance field.
For ID 1 at index 2, the payment of 15 must be subtracted from the 990 and result placed in balance which in this case was 975.
For ID 1 at index 3, the payment of 20 must be subtracted from the 975 and result placed in balance which in this case was 955.
For ID 2 at index 1, the payment of 5 must be subtracted from the amount of 200 and result of 195 placed in balance field.
For ID 2 at index 2, the payment of 5 must be subtracted from the 195 and result of 190 placed in balance field.
df['bal']=df['amount']-df.groupby('ID')['payment'].transform('cumsum')
df
ID payment amount balance bal
0 1 10 1000 990 990
1 1 15 1000 975 975
2 1 20 1000 955 955
3 2 5 200 195 195
4 2 5 200 190 190