如何从numpy datetime64继承？例如,使用标准日期时间,我可以轻松地子类化：

import datetime as dt

class SubFromDateTime(dt.datetime):
    def __new__(self):
        return dt.datetime.__new__(self, 2012, 1, 1)

print type(SubFromDateTime())

>>> 
<class '__main__.SubFromDateTime'>

但是,使用datetime64,以下内容始终返回datetime64参考,而不是我的课程…

from numpy import datetime64

class SubFromDT64(datetime64):
    def __new__(self):
        return datetime64.__new__(self, '20120101')

print type(SubFromDT64())

>>>
<type 'numpy.datetime64'>

我怎样才能解决这个问题？我基本上想为datetime64写一个简单的包装器,它使我可以添加自定义函数,例如使用简单的.Month()方法获取给定日期的月份.在上面的示例中,我可以轻松地添加方法,在下面的示例中,它将永远无法识别我的方法,并认为它是datetime64对象.

解决方法:

我结束了子类化ndarray的创建,它创建了datetime64数组.就我的目的而言,它就像是一种魅力.如果有人对这里的代码感兴趣：

import numpy as np

class Date64(np.ndarray):
    def __new__(cls, data):
        data = np.asarray(data, dtype='datetime64')
        if (data.dtype != 'datetime64[D]'):
            raise Exception('Unable to parse dates adequately to datetime64[D]: %s' % data)
        obj = data.view(cls)
        return obj

    def Year(self):
        return self.astype('datetime64[Y]').astype(int) + 1970

    def Month(self):
        return self.astype('datetime64[M]').astype(int) % 12 + 1

    def Day(self):
        return (self - self.astype('datetime64[M]') + 1).astype(int)

    def ISO(self):
        if (self.shape):
            out = zip(self.Year(), self.Month(), self.Day())
            iso = [ '%04d-%02d-%02d' % each for each in out ]
        else:
            iso = '%04d-%02d-%02d' % (self.Year(), self.Month(), self.Day())
        return iso

    def Export(self):
        return self

    def __array_finalize__(self, obj):
        if obj is None:
            return


if (__name__ == '__main__'):
    a = [ dt.date(2013, 1, 1), '2012-03-01', '2012-07-02', '2012-01-03', '2012-01-04', '2011-01-05' ]
    b = Date64(a)

    print b
    print b.ISO()