On Fri, Jan 15, 2016 at 11:32 PM, Cameron Simpson <c...@zip.com.au> wrote: > On 15Jan2016 23:05, boB Stepp <robertvst...@gmail.com> wrote: >> >> On Fri, Jan 15, 2016 at 10:53 PM, Cameron Simpson <c...@zip.com.au> wrote: >>>>>>> >>>>>>> things.insert(-1, 'What the heck?!?') >>>>>>> things >>>> >>>> >>>> [0, 'Hmm...', 3, 'WhackABunny', 6, 'What the heck?!?', '?'] >>>> >>>> "...at the index..." to me would mean that 'What the heck?!?' should >>>> become the last item in the list. Again, the interpreter help gave >>>> what I was expecting. >>> >>> >>> >>> To me it means "insert 'x' so that its index is 'i'". >> >> >> But that's my point! In my example x (here 'What the heck?!?') is >> *not* at index i (here, -1). Instead it winds up at index -2. But >> this fits in perfectly with the interpreter help, since it winds up >> *before* index i (-1). > > > Ah, but -1 isn't the "real" index. It is a convenient value for computing > the real index if you want to figure things out from the end of the list > instead of the start. In your example above, the real index is 5. As you > would get from things.index('?') before the insert. So your insert really > means: > > things.insert(5, 'What the heck?!?')
Or, actual index = len(things) + (-1) before I do the insert. Another subtlety for negative indexing to file away! Thanks, Cameron. That wraps up things nicely for me. -- boB _______________________________________________ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor