# [Tutor] Question regarding lists and manipulating items in lists.

Scurvy Scott etanes.rm at gmail.com
Wed Jan 16 01:23:27 CET 2013

```On Tue, Jan 15, 2013 at 4:01 PM, Steven D'Aprano <steve at pearwood.info> wrote:
> On 16/01/13 10:40, Scurvy Scott wrote:
> [...]
>
>> Anyways, the problem I'm having is I'm not really sure how to search a
>> list
>> for multiple elements and remove just those elements. Below is my code so
>> far, and information y'all could provide would be appreciated. Thanks.
>
>
> Actually, your problem so far is that you aren't even producing a list of
> elements at all, you keep creating a *single* element, then throwing it
> away when you generate the next Fibonacci number.
>
> Also, you, or more likely Gmail, lost the indentation in your code, so I'm
> going to have to guess what you intended rather than what you have. That's
> because you are sending HTML email, which eats spaces.
>
>
>
>> import mingus.core.notes as notes
>> #fibonacci
>> def fib(num1,num2):
>> a, b = 0, 1
>> for i in xrange(num1,num2):
>> c = b % 12 #modulo 12 on each generated fibonacci number
>> a_list= [notes.int_to_note(c)] #using Mingus to translate the Fib mod12
>> numbers into notes and then (I think) storing each one as an element in a
>> list?
>> a, b = b, a+b #this is just the algorithm for the fibonacci numbers
>
>
>
> Firstly, I recommend that you follow the principle "separation of concerns".
> Keep a separate function for each part of the problem:
>
> * generate Fibonacci numbers;
> * turn them into notes;
>
>
> So here I extract out of your code (untested!) a generator which produces
> an infinite series of Fibonacci numbers, one at a time:
>
> def fib():
>
>     a, b = 0, 1
>     while True:
>         yield b
>
>         a, b = b, a+b
>
>
> This is untested, I may have got it wrong.
>
> Next, a function to generate notes from those Fibonacci numbers:
>
>
> def make_notes(num_notes):
>     it = fib()
>     for i in range(num_notes):
>         n = next(it) % 12  # get the next Fibonacci number, modulo 12
>         notes.append(notes.int_to_note(n))
>     return notes
>
>
> That returns a list of notes.
>
>
> Does that help? Start with that, and see how you go.
>
>
>
> --
> Steven
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Steve
After playing with your example I keep being told that list has no
attribute int_to_note. I know what the problem is, I just don't know
how to fix it.
Also, I believe I've fixed my email so it will no longer be in HTML or
anything fancy, just plain text.

So right now my code is:

import mingus.core.notes as notes

#fibonacci
def fib():
a, b = 0, 1
while True:
yield b
a, b = b, a+b

def make_notes(num_notes):
it = fib()
notes = []
for i in range(num_notes):
n = next(it) % 12
notes.append(notes.int_to_note(n))
return notes

Which is pretty different from what my original code was. The
generator function doesn't actually do anything when called, it just
tells me it's a generator function and where it's located. And like I
said the listing function doesn't want to comply with the module being
called under append method. My code was working almost as I intended
it to, it just wasn't creating a list properly of everything, which I
didn't notice until after one of you guys mentioned it to me. Now I
see it and I can sorta visualize what I'm supposed to do, but can't
see what to do to fix it, if that makes any sense.
```