Python 子类化datetime64
如何从numpy datetime64生成子类?例如,使用标准日期时间,我可以轻松地将以下子类化:Python 子类化datetime64,python,numpy,subclass,datetime64,Python,Numpy,Subclass,Datetime64,如何从numpy datetime64生成子类?例如,使用标准日期时间,我可以轻松地将以下子类化: import datetime as dt class SubFromDateTime(dt.datetime): def __new__(self): return dt.datetime.__new__(self, 2012, 1, 1) print type(SubFromDateTime()) >>> <class '__main__
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'>
将日期时间导入为dt
类SubFromDateTime(dt.datetime):
定义新的(自我):
返回dt.datetime.\uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu
打印类型(SubFromDateTime())
>>>
但是,使用datetime64时,以下始终返回datetime64引用,而不是我的类
from numpy import datetime64
class SubFromDT64(datetime64):
def __new__(self):
return datetime64.__new__(self, '20120101')
print type(SubFromDT64())
>>>
<type 'numpy.datetime64'>
从numpy导入日期时间64
类子romdt64(日期时间64):
定义新的(自我):
返回日期时间64.\uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu
打印类型(SubFromDT64())
>>>
我怎样才能解决这个问题?我基本上想为datetime64编写一个简单的包装器,它允许我添加自定义函数,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,它永远不会识别我的方法并认为它是datetime64对象。我最终将ndarray子类化,从而创建了datetime64数组。对我来说,它就像一个符咒。如果有人对此感兴趣,请输入以下代码:
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()
作为旁注,将
\uuu new\uuu
的第一个参数self
而不是cls
调用有点误导。另外,为什么不使用super
?无论如何,对于一般问题,当您调用\uuuuu new\uuuu(cls)
时,类型通常应该返回cls
的实例(或其子类),但没有规则规定它们必须返回,如果它们不返回,您也无能为力。对于numpy特定的问题…可能有答案,但我不知道它在我的头顶上,所以希望其他人知道。:)我尝试过的一件快速的事情是更改\uuuu class\uuuu
属性,但是NumPy将其基类型声明为非堆类型,所以这不起作用……最后一件事:为什么要尝试这样做?如果将这些内容存储在ndarray
中,则dtype
将是datetime64
、object
,或者是一个自定义的dtype
,它将值存储为datetime64
,并在C API函数中将其视为datetime64
,但在为Python设置框时会自动转换它们。除非您想要对象
,否则类型是否继承datetime64
,实际上并不重要。谢谢您的尝试。我想创建子类,因为我想保持datetime64的原始行为,但添加一些自定义函数。就像可以将子类化为ndarray(有很多这样的例子)一样,我希望将非常类似的datetime64类分为子类。