[Tutor] understanding join

[John Fouhy]

On 31/07/2008, Steve Poe <steve.poe at gmail.com> wrote:
>  Good point. I guess I am surprised a little that Python does not error
>  on that you cannot assign a variable to a module name.  I know I need
>  to learn proper coding techniques.

Well, that wouldn't really work because you don't know what other
modules people have.

>  Okay, I can see the order of the join is the same as mine, but
>  the join still seems to be out of sequence.  I am thinking it should be
>  'abcABC' or 'ABCabc' not at the beginning, middle, and end of the
>  original string. At least, I am trying to wrap my head around its
>  usefulness.

Say I have a sequence seq and a string s, and I call s.join(seq).
Here's what it does:

s.join(seq) == seq[0] + s + seq[1] + s + seq[2] + s + ...  + seq[-2] +
s + seq[-1]

So if you call 'abc'.join('ABC'), you get:

   'ABC'[0] + 'abc' + 'ABC'[1] + 'abc' + 'ABC'[2]

which is:

   'A' + 'abc' + 'B' + 'abc' + 'C'

Hope this helps.

-- 
John.