Insert item before each element of a list

[Prasad, Ramit]

Agon Hajdari wrote:
> On 10/08/2012 11:15 PM, Prasad, Ramit wrote:
> > Agon Hajdari wrote:
> >>
> >> On 10/08/2012 09:45 PM, Chris Kaynor wrote:
> >>> [('insertme', i) for i in x]
> >>
> >> This is not enough, you have to merge it afterwards.
> >
> > Why do you say that? It seems to work just fine for me.
> >
> >>>> x
> > [0, 1, 2, 3, 4]
> >>>> [('insertme', i) for i in x]
> > [('insertme', 0), ('insertme', 1), ('insertme', 2), ('insertme', 3), ('insertme', 4)]
> >
> >>
> >> y = [item for tup in y for item in tup]
> 
> I think he wanted to have a 'plain' list
> a = [0, 1, 0, 2, 0, 3]
> and not
> a = [(0, 1), (0, 2), (0, 3)]

You are absolutely correct. I missed that when I tried it.
Instead of the nested list comprehension, I might have used
map instead.

>>> y = [('insertme', i) for i in x]
>>> z = []
>>> _ = map( z.extend, y )
>>> z
['insertme', 0, 'insertme', 1, 'insertme', 2, 'insertme', 3, 'insertme', 4]

I am not sure which is more Pythonic, but to me map + list.extend tells
me more explicitly that I am dealing with an iterable of iterables.
It might make more sense to only to me though.


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