> >> Could you explain to me how you'd like this to be fixed? If the >> matrix becomes a container of 1-d arrays, then you can no longer >> expect x[:,0] to return a column vector -- which was one >> of the reasons the matrix class was created. While not >> entirely consistent, one workaround would be to detect >> when a matrix is a "vector", and then do 1-d-like indexing >> on it. >> > > > > Letting M be a matrix and A=M.A, and i and j are integers. > I would want two principles to be honored. > > 1. ordinary Python indexing produces unsurprising results, > so that e.g. M[0][0] returns the first element of the matrix > 2. indexing that produces a 2-d array when applied to A > will produce the equivalent matrix when applied to M > > There is some tension between these two requirements, > and they do not address your specific example. > > Various reconciliations can be imagined. > I believe a nice one can be achieved with > a truly minimal change, as follows. > > Let M[i] return a 1d array. (Unsurprising!) > This is a change: a matrix becomes a container > This is a concrete proposal and I don't immediately have a problem with it (other than it will break code and so must go in to 1.1). > Let M[:,i] and M[i,:] behave as now. > Some would expect M[i,:] and M[i] to be the same thing, but I would be willing to squelsh those expectations if many can agree that M[i] should return an array. > In addition, as a consistency measure, one might > ask that M[i,j] return a 1 x 1 matrix. (This is > of secondary importance, but it follows the > principle that the use of multiple indexes > produces matrices.) > I'm pretty sure that wasn't the original "principle", but again this is not unreasonable. > Right now I'm operating on caffeine instead of sleep, > but that looks right ... > > Alan Isaac > >
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