On Jul 1, 12:35 pm, Tobiah <[EMAIL PROTECTED]> wrote: > list.append([1,2]) will add the two element list as the next > element of the list. > > list.extend([1,2]) is equivalent to list = list + [1, 2] > and the result is that each element of the added list > becomes it's own new element in the original list. > > Is that the only difference? > > From the manual: > > s.extend(x) | same as s[len(s):len(s)] = x > > But: (python 2.5.2) > > >>> a > [1, 2, 3] > >>> a[len(a):len(a)] = 4 > > Traceback (most recent call last): > File "<stdin>", line 1, in <module> > TypeError: can only assign an iterable > > > > Also, what is the difference between list[x:x] and list[x]? > > >>> a[3:3] = [4] > >>> a > > [1, 2, 3, 4] > ** Posted fromhttp://www.teranews.com**
In this example: > s.extend(x) | same as s[len(s):len(s)] = x x _must_ be iterable. As the error states, `4` is not iterable. the s[start:stop] notation is called slicing: >>> x = range(10) >>> x[0] 0 >>> x[1] 1 >>> x[0:1] [0] >>> x[0:2] [0, 1] >>> x[0:3] [0, 1, 2] >>> x[1:3] [1, 2] >>> x[5:-1] [5, 6, 7, 8] >>> x[5:] [5, 6, 7, 8, 9] In general `x[len(x):len(x)] = seq` is a stupid way to extend a list, just use .extend or +=. Matt -- http://mail.python.org/mailman/listinfo/python-list
