如何从熊猫df中提取年份作为数组

Question

如何从熊猫df日期时间对象中提取年份作为数组？尝试时 years = ([employees['Hiring Date'].dt.year])，“年”以列表的形式出现。

Answer 1

这可能对您不起作用，因为我可能误读了您的帖子，但我会尝试：

years = df['hiring date'].values

然后：

years = np.array(years)

Answer 2

• 使用pandas.Series.to_numpy

from datetime import datetime
import pandas as pd

# data
data = {'Hiring Date': pd.bdate_range(datetime(1971, 1, 1), freq='2m', periods=40).tolist()}

# dataframe
employees = pd.DataFrame(data)

# extract years
years = employees['Hiring Date'].dt.year.to_numpy()

print(years)
[1971 1971 1971 1971 1971 1971 1972 1972 1972 1972 1972 1972 1973 1973
 1973 1973 1973 1973 1974 1974 1974 1974 1974 1974 1975 1975 1975 1975
 1975 1975 1976 1976 1976 1976 1976 1976 1977 1977 1977 1977]

print(type(years))
<class 'numpy.ndarray'>

print(years.shape)
(40,)