[Numpy-discussion] Superclassing numpy.matrix: got an unexpected keyword argument 'dtype'
Pierre GM
pgmdevlist@gmail....
Wed Dec 10 10:32:50 CST 2008
Robert,
Transforming your matrix to a list before computation isn't very
efficient. If you do need some extra parameters in your __init__ to be
compatible with other functions such as asmatrix, well, just add them,
or use a coverall **kwargs
def __init__(self, instruments, **kwargs)
No guarantee it'll work all the time.
Otherwise, please have a look at:
http://docs.scipy.org/doc/numpy/user/basics.subclassing.html
and the other link at the top of that page. In your case, I'd try to
put the initialization in the __array_finalize__.
On Dec 10, 2008, at 7:15 AM, <Robert.Conde@sungard.com> <Robert.Conde@sungard.com
> wrote:
> Hello,
>
> I'm using numpy-1.1.1 for Python 2.3. I'm trying to create a class
> that acts just like the numpy.matrix class with my own added methods
> and attributes. I want to pass my class a list of custom
> "instrument" objects and do some math based on these objects to set
> the matrix. To this end I've done the following:
>
> from numpy import matrix
>
> class rcMatrix(matrix):
> def __init__(self,instruments):
> """Do some calculations and set the values of the matrix."""
> self[0,0] = 100 # Just an example
> self[0,1] = 100 # The real init method
> self[1,0] = 200 # Does some math based on the input objects
> self[1,1] = 300 #
> def __new__(cls,instruments):
> """When creating a new instance begin by creating an NxN
> matrix of
> zeroes."""
> len_ = len(instruments)
> return matrix.__new__(cls,[[0.0]*len_]*len_)
>
> It works great and I can, for example, multiply two of my custom
> matrices seamlessly. I can also get the transpose. However, when I
> try to get the inverse I get an error:
>
>> rcm = rcMatrix(['instrument1','instrument2'])
>> print rcm
> [[ 100. 100.]
> [ 200. 300.]]
>> print rcm.T
> [[ 100. 200.]
> [ 100. 300.]]
>> print [5,10] * rcm
> [[ 2500. 3500.]]
>> print rcm.I
> Traceback (most recent call last):
> File "[Standard]/deleteme", line 29, in ?
> File "C:\Python23\Lib\site-packages\numpy\core\defmatrix.py", line
> 492, in getI
> return asmatrix(func(self))
> File "C:\Python23\Lib\site-packages\numpy\core\defmatrix.py", line
> 52, in asmatrix
> return matrix(data, dtype=dtype, copy=False)
> TypeError: __init__() got an unexpected keyword argument 'dtype'
>
>
>
> I've had to overwrite the getI function in order for things to work
> out:
>
> def getI(self): return matrix(self.tolist()).I
> I = property(getI, None, doc="inverse")
>
> Is this the correct way to achieve my goals?
>
> Please let me know if anything is unclear.
>
> Thanks,
>
> Robert Conde
>
>
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