[FIXED] how to insert "X" between rows of dataframe based on dates

Issue

ID	Date	dummy
0	2019-01-03 20:00:00
1	2019-01-04 14:30:00	x
2	2019-01-04 16:00:00	x
3	2019-01-04 20:00:00	x

wanted to know how would I be able to insert "X" into the dummy column based on date selection. For example I would like to input an "X" starting 2019-01-04 14:30:00 to 2019-01-04 20:00:00

I know I could just select df\["dummy"\]\[1:3\] = "X" to accomplish this but not too sure how to grab from the dates column.

Solution

Use between to create a boolean Series for dates between your boundaries, and np.where to select between 'x' and '':

df['dummy'] = np.where(df['Date'].between('2019-01-04 14:30:00',
                                          '2019-01-04 20:00:00'),
                       'x', '')

Or, with boolean indexing:

df.loc[df['Date'].between('2019-01-04 14:30:00', '2019-01-04 20:00:00'),
       'dummy'] = 'x'

Output:

   ID                Date dummy
0   0 2019-01-03 20:00:00      
1   1 2019-01-04 14:30:00     x
2   2 2019-01-04 16:00:00     x
3   3 2019-01-04 20:00:00     x

Answered By - mozway