40 - 列级 - df[""] = df[""].xx - 数据截取、数据转换日期

数据截取

df['日期按日'] = df['日期按日'].astype("str")
df['日期按日'] = df['日期按日'].str[0:10]

可以获得日期，把2024-01-01 00:00:00剪切得到2024-01-01

import numpy as np
import pandas as pd
df = pd.DataFrame(data=[{"A":"2024-01-01 00:00:00", "B":"a"}, {"A":"2024-01-01 00:00:00", "B":"b"}])
print(df)
df['A'] = df['A'].astype("str")
df['A'] = df['A'].str[0:10]
print(df)

数据转换日期获得星期几

可以获得日期，把2024-01-01 00:00:00获得星期几

df['星期几'] = pd.to_datetime(df['星期几'])
df['星期几'] = df['星期几'].dt.dayofweek + 1

import numpy as np
import pandas as pd
df = pd.DataFrame(data=[{"A":"2024-01-01 00:00:00", "B":"a"}, {"A":"2024-01-09 00:00:00", "B":"b"}])
print(df)
df['A'] = pd.to_datetime(df['A'])
df['星期几'] = df['A'].dt.dayofweek + 1
print(df)