Pandas Dataframe datetime condition

Question

I have the following dataframe and would like to create a new column based on a condition. The new column should contain 'Night' for the hours between 20:00 and 06:00, 'Morning' for the time between 06:00 and 14:30 and 'Afternoon' for the time between 14:30 and 20:00. How can I formulate and apply such a condition best way?

import pandas as pd

df = {'A' : ['test', '2222', '1111', '3333', '1111'],
        'B' : ['aaa', 'aaa', 'bbbb', 'ccccc', 'aaa'],
        'Date' : ['15.07.2018 06:23:56', '15.07.2018 01:23:56', '15.07.2018 06:40:06', '15.07.2018 11:38:27', '15.07.2018 21:38:27'],
        'Defect': [0, 1, 0, 1, 0]
        }

df = pd.DataFrame(df)
df['Date'] = pd.to_datetime(df['Date'])

Corralien · Accepted Answer · 2022-02-12 14:12:54Z

3

You can use np.select:

from datetime import time

condlist = [df['Date'].dt.time.between(time(6), time(14, 30)),
            df['Date'].dt.time.between(time(14,30), time(20))]

df['Time'] = np.select(condlist, ['Morning', 'Afternoon'], default='Night')

Output:

>>> df
      A      B                Date  Defect     Time
0  test    aaa 2018-07-15 06:23:56       0  Morning
1  2222    aaa 2018-07-15 01:23:56       1    Night
2  1111   bbbb 2018-07-15 06:40:06       0  Morning
3  3333  ccccc 2018-07-15 11:38:27       1  Morning
4  1111    aaa 2018-07-15 21:38:27       0    Night

Note, you don't need the condition for 'Night':

df['Date'].dt.time.between(time(20), time(23,59,59)) \
| df['Date'].dt.time.between(time(0), time(6))

because np.select can take a default value as argument.

answered Feb 12, 2022 at 14:12

Corralien

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1 Comment

Tom Over a year ago

Thank you, works fine for me :)!

gold_cy · Accepted Answer · 2022-02-12 14:08:28Z

1

You can create an index of the date field and then use indexer_between_time.

idx = pd.DatetimeIndex(df["Date"])
conditions = [
    ("20:00", "06:00", "Night"),
    ("06:00", "14:30", "Morning"),
    ("14:30", "20:00", "Afternoon"),
]

for cond in conditions:
    start, end, val = cond
    df.loc[idx.indexer_between_time(start, end, include_end=False), "Time_of_Day"] = val

      A      B                Date  Defect Time_of_Day
0  test    aaa 2018-07-15 06:23:56       0     Morning
1  2222    aaa 2018-07-15 01:23:56       1       Night
2  1111   bbbb 2018-07-15 06:40:06       0     Morning
3  3333  ccccc 2018-07-15 11:38:27       1     Morning
4  1111    aaa 2018-07-15 21:38:27       0       Night

answered Feb 12, 2022 at 14:08

gold_cy

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