removing, replacing and moving contents in a list

[pavlos03]

Hi everyone again, yet another question on lists

consider this list:

Python Code:

mylist=[]
mylist.append(['B2', ['C3', 'C4', ['D5', 'D6']], 'B7','B8', ['C9', [[['F10'],'E11'],'D12']]])

I want to iterate through all the contents and for every string that contains 'B' to remove them and place all of them in a new sublist one level deeper in a way that the list prints

Python Code:

[['B2','B7','B8'], ['C3', 'C4', ['D5', 'D6']], ['C9', [[['F10'],'E11'],'D12']]]

I've using list.remove(item) while in a 'for item in list' loop and it reduces the index by one messing up everything.

so i decided to create a new list with the Strings positioned the way i want:

Python Code:

def NewList(thelist):
    sublist = []
    sublist2=[]
    newlist= []
    for item in thelist:
        if hasattr(item,"__iter__"):
            for subitem in item:
                sublist.append(subitem)
        elif "B" in item:
                sublist2.append(item)
        else:
            newlist.append(item)
           
    newlist.append(sublist2)
   
    if sublist: newlist.append(NewList(sublist))
   
    return newlist

but this returns:

python Code:

[[], [['B2', 'B7', 'B8'], ['C3', 'C4', 'C9', [], ['D5', 'D6', 'D12', [], ['E11', [], ['F10', []]]]]]]

and i don't understand what are the empty slots or the extra brackets...

any help appreciated !

regards,

Pav

[Steve Baer]

Hi Pav,
I would recommend posting this question on stackoverflow.com. It is a generic question about python lists that someone there is probably going to do a much better job at answering than I can.

You can probably figure out what is going on by placing a breakpoint at the beginning of your function and stepping through the code to understand why the empty lists are being added.
Thanks,
-Steve

[Goswin]

Hi Pavlos03,

Like Steve said, StackOverflow is really a good resource for these kind of questions. It's amazing. On such questions you might get an answer within a few minutes.

In your case the empty brackets are empty lists. You can avoid them by adding an if statement before newlist.append. But i am not sure if that gets you the desired return :

python Code:

if sublist2: newlist.append(sublist2)

That is the beauty of Pythons dynamic typing: after an if statement an []empty list, ()empty tuple, 0 , 0.0 and "" an empty string will all evaluate as False.

Steve, I hope you read this,
how about starting a page using the stackoverflow model for RhinoPython ?
like one of those:
http://stackexchange.com/sites#
here for new ones:
http://area51.stackexchange.com/

[Steve Baer]

I think you need an awful lot of people to push to get a new site on stackexchange. I've thought about doing a better job of using stackoverflow for Rhino SDK related questions in the past, but never really figured out a good approach for this.

[frankfralick]

What if the proposal for a stack exchange site was more related to 3d modelling application programming? I spend a lot of time on rhino but I spend more time programming for other applications in the same general domain. I am sure that a lot of people that follow this forum would be interested in a stack exchange site that included rhino and the other applications we have to mess with daily.

[Goswin]

Hi Steve, It does not seem to be so difficult to launch a Stack site, but aparently you need 15 questions per day to get a site through beta. for example: http://area51.stackexchange.com/proposals/5022/3d-graphics-modeling-applications was closed.
Currently there are only 2-3 per day on RhinoPython but maybe the amount of questions will increase after the launch of Rh5.
I think a site could cover mainly RhinoPython and Common but maybe C++ , vbscript and interaction with other CAD packages( Revit..) too.
Was David considering it for Grashopper ?