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Newsgroups: comp.lang.python
Date: Thu, 3 Dec 2015 18:11:24 -0800 (PST)
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Subject: Re: Is there a way to set several list elements a same value with one line code
From: Robert <rxjwg98@gmail.com>
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On Thursday, December 3, 2015 at 7:59:16 PM UTC-5, MRAB wrote:
> On 2015-12-04 00:30, Robert wrote:
> > Hi,
> >
> > I remember that there is a way to set several list elements a same value with
> >   one line code. Excuse me, I don't remember the accurate syntax on the code
> >   snippet. But the basic format looks like this.
> >
> > 1. There is a four-element list, such as:
> >     bb=[[[]],[[]],[[]],[[]]]
> > 2. An assignment line is here:
> >     bb[0]='a'
> > 3. Then, all 4 element of bb is set with the above value.
> >     bb=[['a'],['a'],['a'],['a']]
> >
> > The above three line codes are what I guess (I forgot the original tutorial
> >   now). Do you remember there is such a list application?
> >
> Do you mean this behaviour:
> 
> >>> bb=[[[]]] * 4
> >>> print(bb)
> [[[]], [[]], [[]], [[]]]
> >>> bb[0][0]='a'
> >>> print(bb)
> [['a'], ['a'], ['a'], ['a']]
> 
> ?
> 
> That's because the bb contains 4 references to the same list.

Yes! What you post is I want. Thanks.