Python Pandas-根据给定的窗口并从特定值开始计算特定列的总和

Question

I am trying to create a new column in a Python Pandas data frame that contains summed values from another column within a specified range and starting at a certain row. For example, in the data frame below, I want the sum of the Value column starting at row 3 (using index row numbers) for Trace 1. However, I also need to repeat the same criteria for Trace 2. Moreover, I need to start at the same Sample number for each Trace. Any ideas?

Answer 1

IIUC,

groupby + rolling + sum

df = pd.DataFrame({'trace': [1]*5 + [2]*5, 'sample': list(range(1,6))*2,
                  'value': [0.25, 0.63, 0.98, 0.48, 0.52,0.79, 0.63, 0.11, 0.29, 0.81]})
df.groupby('trace').value.rolling(4).sum()

1      0     NaN
       1     NaN
       2     NaN
       3    2.34
       4    2.61
2      5     NaN
       6     NaN
       7     NaN
       8    1.82
       9    1.84