On 12/15/10 7:16 AM, liji.ma...@gmail.com wrote:
Hi Sage group:I have met a problem. The code is as follow. import numpy as np A = np.mat([[1, 2, 3], [4, 5, 6], [7, 8, 9]]) print A[:, 1].shape for i in range(0, 3): print A[:, i].shape the result is (1, 3) (3, 1) (3, 1) (3, 1) Is there any difference between "print A[:, 1]" and "print A[:, i]"?
A[:,i] gives back the ith column. A[:,1] gives back the column with index 1 (i.e., the second column, since the columns are numbered starting with zero). We support the same syntax for Sage matrices [1].
I'd point you to the numpy documentation (you might try typing "numpy tutorial" in google), but scipy.org (where the tutorial is located) seems to be down at the moment.
Thanks, Jason [1] http://sagemath.org/doc/reference/sage/matrix/docs.html#indexing -- To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org
