Le mercredi 03 décembre 2008, Sébastien Barthélemy a écrit : > Hello, Hi Sebastien!
> I'm trying to write a small library of differential geometry, and I > have some trouble subclassing ndarray. > I'd like an HomogeneousMatrix class that subclasse ndarray and > overloads some methods, such as inv(). > Here is my first try, the inv() function and the inv_v1() method work > as expected, but the inv_v2() and inv_v3() methods do not change the > object at all. Can somebody explain me what is happening here ? > > import numpy as np > def inv(H): > """ > inverse of an homogeneous matrix > """ > R = H[0:3,0:3] > p = H[0:3,3:4] > return np.vstack( (np.hstack((R.T,-np.dot(R.T,p))), [0,0,0,1])) > > class HomogeneousMatrix(np.ndarray): > def __new__(subtype, data=np.eye(4)): > subarr = np.array(data) > if htr.ishomogeneousmatrix(subarr): > return subarr.view(subtype) > else: > raise ValueError > def inv_v1(self): > self[0:4,0:4] = htr.inv(self) > def inv_v2(self): > data = htr.inv(self) > self = HomogeneousMatrix(data) > def inv_v3(self): > self = htr.inv(self) There is something I missed: what is htr? I guess htr.inv is the inv function defined before the class. Another point: it seems weird to me that, in the class' methods inv_v2 and inv_v3, you 'unref' the previous instance of HomogeneousMatrix and link the 'self' label to a new instance... In inv_v1, you just modify the coefficient of the Homogeneous Matrix with the coefficient of htr.inv(self) -- Fabrice Silva <[EMAIL PROTECTED]> LMA UPR CNRS 7051 - équipe S2M _______________________________________________ Numpy-discussion mailing list Numpy-discussion@scipy.org http://projects.scipy.org/mailman/listinfo/numpy-discussion
