【python】numpy.datetime64( ) 时间和 datetime.datetime 互转

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首先定义几个时间变量datetime、Timestamp、numpy.datetime64：

import datetime
import numpy as np
import pandas as pd
dt = datetime.datetime(2018, 9, 1)
# A strange way to extract a Timestamp object, there's surely a better way?
ts = pd.DatetimeIndex([dt])[0]
dt64 = np.datetime64(dt)
dt
Out[67]: datetime.datetime(2018, 9, 1, 0, 0)

ts
Out[68]: Timestamp('2018-09-01 00:00:00')

dt64
Out[69]: numpy.datetime64('2018-09-01T00:00:00.000000')

转换datetime对象

• 传入Timestamp(‘2018-09-01 00:00:00’)格式或者datetime格式均可

np.datetime64(ts)
Out[84]: numpy.datetime64('2018-09-01T00:00:00.000000')

np.datetime64(dt)
Out[85]: numpy.datetime64('2018-09-01T00:00:00.000000')

转换numpy.datetime64对象

1、直接用astype的方法进行转化

dt64.astype(datetime.datetime)
Out[74]: datetime.datetime(2018, 9, 1, 0, 0)

2、先转化为timestamp，再转化为datetime

• 先转化为timestamp：

(dt64-np.datetime64('1970-01-01T00:00:00Z')) / np.timedelta64(1, 's')
Out[72]: 1535760000.0

• 再将timestamp转为datetime格式

datetime.datetime.fromtimestamp((dt64-np.datetime64('1970-01-01T00:00:00Z')) / np.timedelta64(1, 's'))
Out[76]: datetime.datetime(2018, 9, 1, 8, 0)