Python PANDAS: Stack By Enumerated Date To Create Records Vectorized

I have a dataframe in the following general format: id,transaction_dt,units,measures 1,2018-01-01,4,30.5 1,2018-01-03,4,26.3 2,2018-01-01,3,12.7 2,2018-01-03,3,8.8 What I am tryi

Solution 1:

You can use numpy.repeat for duplicate indices by column units with loc for duplicates rows. Last per each indices get count by cumcount, convert to_timedelta and add to column transaction_dt. Last reset_index for default unique indeices:

df = df.loc[np.repeat(df.index, df['units'])]
df['transaction_dt'] += pd.to_timedelta(df.groupby(level=0).cumcount(), unit='d')
df = df.reset_index(drop=True)
print (df)
    id transaction_dt  units  measures
0    1     2018-01-01      4      30.5
1    1     2018-01-02      4      30.5
2    1     2018-01-03      4      30.5
3    1     2018-01-04      4      30.5
4    1     2018-01-03      4      26.3
5    1     2018-01-04      4      26.3
6    1     2018-01-05      4      26.3
7    1     2018-01-06      4      26.3
8    2     2018-01-01      3      12.7
9    2     2018-01-02      3      12.7
10   2     2018-01-03      3      12.7
11   2     2018-01-03      3       8.8
12   2     2018-01-04      3       8.8
13   2     2018-01-05      3       8.8