如何在 pandas 中相互添加/减去行值？

Question

I have a DataFrame that looks like:

    credit  debit
0   0.0     89.40
1   0.0     4.33
2   0.0     12.00
3   500.0   0.00
4   0.0     5.40

If I know the current balance is 300, how do I make a balance column that subtracts the debit from each row and adds the credit from each row?

I have tried using df.sub but I am having no luck...

The Balance column should look like:

balance
300.00
389.40
393.33
405.33
-94.27

here is the code for the sample DataFrame

df = pd.DataFrame({'credit': {0: 0.0, 1: 0.0, 2: 0.0, 3: 500.0, 4: 0.0},'debit': {0: 89.4, 1: 4.33, 2: 12.0, 3: 0.0, 4: 5.4}})

Answer 1

Like this:

In [511]: df['balance'] = df.debit.cumsum() + 300 - df.credit.cumsum()

In [512]: df
Out[512]: 
   credit  debit  balance
0     0.0  89.40   389.40
1     0.0   4.33   393.73
2     0.0  12.00   405.73
3   500.0   0.00   -94.27
4     0.0   5.40   -88.87

OR:

In [513]: df['balance'] = df.debit.cumsum().sub(df.credit.cumsum()).add(300)

Answer 2

I am thinking that you are looking for a "running balance" of the dataframe. If yes, continue to read else discard.

import pandas as pd
from itertools import accumulate
import operator
import numpy as np

DF = pd.DataFrame({'credit': {0: 0.0, 1: 0.0, 2: 0.0, 3: 500.0, 4: 0.0},
 'debit': {0: 89.4, 1: 4.33, 2: 12.0, 3: 0.0, 4: 5.4}})

Initial_Balance = 300
Running_Balance = np.array(list(accumulate(DF.debit-DF.credit, func=operator.add)))+Initial_Balance
DF["Running_Balance"] = Running_Balance
print(DF)

This gives the following output.

   credit  debit  Running_Balance
0     0.0  89.40           389.40
1     0.0   4.33           393.73
2     0.0  12.00           405.73
3   500.0   0.00           -94.27
4     0.0   5.40           -88.87