问题描述
我有一个从netCDF文件中提取的时间序列，我正在尝试将其转换为日期时间格式。时间序列的格式为自1990年1月1日00:00:00 +10起的天数（+10为格林尼治标准时间：+10）
I have a time series that I have pulled from a netCDF file and I'm trying to convert them to a datetime format. The format of the time series is in 'days since 1990-01-01 00:00:00 +10' (+10 being GMT: +10)
time = nc_data.variables['time'][:]
time_idx = 0 # first timestamp
print time[time_idx]
9465.0
我想要的输出是像这样的日期时间对象（也是GMT +10）：
My desired output is a datetime object like so (also GMT +10):
2015-12-01 00:00:00
尽管我相信我可能使用了错误的方法，但我尝试使用时间模块转换此方法没有太大的成功（我仍然是python和编程的新手）。
I have tried converting this using the time module without much success although I believe I may be using wrong (I'm still a novice in python and programming).
import time
time_datetime = time.strftime('%Y-%m-%d %H:%M:%S', time.gmtime(time[time_idx]*24*60*60))
任何建议表示赞赏，
干杯！
Any advice appreciated,Cheers!
推荐答案
datetime 模块的可能就是您想要的。
The datetime module's timedelta is probably what you're looking for.
例如：
from datetime import date, timedelta
days = 9465 # This may work for floats in general, but using integers
# is more precise (e.g. days = int(9465.0))
start = date(1990,1,1) # This is the "days since" part
delta = timedelta(days) # Create a time delta object from the number of days
offset = start + delta # Add the specified number of days to 1990
print(offset) # >>> 2015-12-01
print(type(offset)) # >>> <class 'datetime.date'>
然后您可以使用和/或操作偏移量对象，或者将其转换为字符串表示形式，但是您可以
You can then use and/or manipulate the offset object, or convert it to a string representation however you see fit.
您可以使用与该日期对象相同的格式，就像您在 time_datetime 中所做的一样：
You can use the same format as for this date object as you do for your time_datetime:
print(offset.strftime('%Y-%m-%d %H:%M:%S'))
输出：
2015-12-01 00:00:00
例如，如果您使用 date 对象，则可以使用 datetime 对象，而不是使用 datetime 对象
Instead of using a date object, you could use a datetime object instead if, for example, you were later going to add hours/minutes/seconds/timezone offsets to it.
除了两行代码外，代码将与上面相同：
The code would stay the same as above with the exception of two lines:
# Here, you're importing datetime instead of date
from datetime import datetime, timedelta
# Here, you're creating a datetime object instead of a date object
start = datetime(1990,1,1) # This is the "days since" part
注意：尽管您未声明它，但另一个答案表明您可能正在寻找时区感知日期时间。在这种情况下， dateutil 是Python 2中的另一种建议。在Python 3中，您想使用 datetime 模块的。
Note: Although you don't state it, but the other answer suggests you might be looking for timezone aware datetimes. If that's the case, dateutil is the way to go in Python 2 as the other answer suggests. In Python 3, you'd want to use the datetime module's tzinfo.
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