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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