The cumulative total value of a particular column in the data frame was added to the last column (Cumsum_d)
Then it became like the picture above (most of the values were mosaic due to circumstances)
But what I want is that the cumulative sum is initialized every time the date changes.
For example, when the date changes, as shown in the picture below,
It's not a 3402.96 value, it's starting to accumulate again at 15.86.
I think the date interval is the same as the 96th row, so we can use the numbers in the index to make a for phrase.
I don't know how to express it because my skills are still humble.
I'm looking for help from talented people.
python for-statement
By default, groupby operations are provided.
import pandas as pd
df = pd.DataFrame({
'date': ['2015-01-01', '2015-01-01', '2015-01-02', '2015-01-02'],
'value': [10, 20, 30, 40]
})
df['csum'] = df.value.groupby(df.date).cumsum()
date value csum
0 2015-01-01 10 10
1 2015-01-01 20 30
2 2015-01-02 30 30
3 2015-01-02 40 70
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