带有Datetime列的pandas条件字符串串联(多项选择)

import pandas as pd

# 创建示例DataFrame
data = {
    'Datetime': ['2020-06-15', '2021-08-20', '2019-11-10', '2022-03-05'],
    'Value': [10, 20, 30, 40]
}
df = pd.DataFrame(data)
df['Datetime'] = pd.to_datetime(df['Datetime'])

# 条件字符串串联
def event_marker(row):
    if (row['Datetime'] >= '2020-01-01') & (row['Datetime'] <= '2020-12-31'):
        return '2020 Event'
    elif (row['Datetime'] >= '2021-01-01') & (row['Datetime'] <= '2021-12-31'):
        return '2021 Event'
    else:
        return 'Other Event'

df['Event'] = df.apply(event_marker, axis=1)

print(df)

import numpy as np

# 使用向量化操作
df['Event'] = np.select(
    [
        (df['Datetime'] >= '2020-01-01') & (df['Datetime'] <= '2020-12-31'),
        (df['Datetime'] >= '2021-01-01') & (df['Datetime'] <= '2021-12-31')
    ],
    [
        '2020 Event',
        '2021 Event'
    ],
    default='Other Event'
)

print(df)