On Tue, Apr 29, 2008 at 11:21 AM, Alan G Isaac <[EMAIL PROTECTED]> wrote: > On Tue, 29 Apr 2008, Keith Goodman apparently wrote: > > I often use x[i,:] and x[:,i] where x is a matrix and i is > > a scalar. I hope this continues to return a matrix. > > 1. Could you give an example of the circumstances of this > use?
In my use i is most commonly an array (i = M.where(y.A)[0] where y is a nx1 matrix), sometimes a list, and in ipython when debugging or first writing the code, a scalar. It would seem odd to me if x[i,:] returned different types of objects based on the type of i: array index idx = M.where(y.A)[0] where y is a nx1 matrix x[dx,:] --> matrix list index idx = [0] x[idx,:] --> matrix? scalar index idx = 0 x[idx,:] --> not matrix > 2. Would any or all of the following be just as good > a result? > a. 1d matrix > b. row and column vectors (1d but "oriented" for > linear algebra purposes) For me, having arrays and matrices is confusing enough. Adding row and column objects sounds even more confusing. > 3. If 2a. and 2b. are no good for you, > a. would e.g. ``x[i:i+1,:]`` be too burdensome? Yes. > b. would ``rows`` and ``columns`` attributes that > yielded matrics be an offsetting convenience? I like the idea, from earlier in the thread, of row and col being iterators for those time when you want to work on one column or row at a time. _______________________________________________ Numpy-discussion mailing list Numpy-discussion@scipy.org http://projects.scipy.org/mailman/listinfo/numpy-discussion
