Paul Appleby wrote: > I saw somewhere on the net that you can copy a list with slicing. So > what's happening when I try it with a numpy array? > >>>> a = numpy.array([1,2,3]) >>>> b = a[:] >>>> a is b > False >>>> b[1] = 9 >>>> a > array([1, 9, 3])
Copy or view -- have a look under the hood: >>> a = numpy.array([1,2,3]) >>> v = a.view() >>> c = a.copy() >>> s = a[:] >>> a.flags["OWNDATA"] True >>> v.flags["OWNDATA"] False >>> c.flags["OWNDATA"] True >>> s.flags["OWNDATA"] False You only get a copy if you ask for one; slicing produces a view. -- https://mail.python.org/mailman/listinfo/python-list
