Thank you Steven D'Aprano and Alan Gauld.
On Mon, Dec 26, 2016 at 4:41 PM, Alan Gauld via Tutor <tutor@python.org>
wrote:
> On 26/12/16 08:03, Sunil Tech wrote:
> > Hi Team,
> >
> > Dictionary is like
> >
> > a = {'a': 'New', 'b': 'Two', 'l': [{'k': 'test', 'm': 'again'}, {'k':
> > 'test', 'm': 'again'}]}
> >
> > I am trying to modify a value in the dictionary value at a['l']
>
> So make life easy for yourself and get rid of the outer dictionary
> and use the python prompt to experiment:
>
> >>> L = [{'k': 'test', 'm': 'again'}, {'k': 'test', 'm': 'again'}]
> >>> [{'k':d['k'],'m':'replaced'} for d in L]
> [{'k': 'test', 'm': 'replaced'}, {'k': 'test', 'm': 'replaced'}]
> >>>
>
> But that's not very general, you really should have a generator
> for the dictionary that has a conditional expression within to
> replace the m. But that means having a generator within a
> comprehension inside a dictionary access.
>
> It's all getting a bit ugly and overly complex and our goal as
> programmers is to write clear, easily maintainable code, so
> this is probably a bad idea.
>
> Better to unroll into an explicit loop and make it obvious
> what you are doing.
>
> for d in a['l']: d['m'] = 'replaced'
>
> Isn't that clearer?
>
> --
> Alan G
> Author of the Learn to Program web site
> http://www.alan-g.me.uk/
> http://www.amazon.com/author/alan_gauld
> Follow my photo-blog on Flickr at:
> http://www.flickr.com/photos/alangauldphotos
>
>
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