如何获得条件累计和

Question

I have a column that requires conditional cumulative sum where a null value resets the cumulation. How do I achieve this?

t = pd.DataFrame([2, 3, None, 1, 4])

# DataFrame
| 0    |
|------|
| 2    |
| 3    |
| NaN  |
| 1    |
| 4    |

# Desired Output
| 0    |
|------|
| 2    |
| 5    |
| NaN  |
| 1    |
| 5    |

Answer 1

Like this:

In [29]: t[0].groupby(t[0].isna().cumsum()).cumsum()                                                                                                                                                        
Out[29]: 
0    2.0
1    5.0
2    NaN
3    1.0
4    5.0
Name: 0, dtype: float64