Namedtuples problem

[Deborah Swanson]

Ben Bacarisse wrote, on February 23, 2017 4:24 PM
> 
> "Deborah Swanson" <python at deborahswanson.net> writes:
> 
> >> -----Original Message-----
> >> From: Erik [mailto:python at lucidity.plus.com]
> >> Sent: Thursday, February 23, 2017 2:09 AM
> >> To: python at deborahswanson.net; python-list at python.org
> >> Subject: Re: Namedtuples problem
> >> 
> >> 
> >> Hi,
> >> 
> >> On 23/02/17 09:38, Deborah Swanson wrote:
> >> > group[[idx][records_idx[label]]]
> >> > gets an IndexError: list index out of range
> >> 
> >> [snip]
> >> 
> >> > Can anyone see why I'm getting this Index error? and how 
> to fix it?
> >> 
> >> It looks to me like you are indexing into a single-element
> >> list that you 
> >> are creating using the literal list syntax in the middle of 
> >> the expression.
> >
> > Actually, group is essentially a 2-element list. Each group 
> has a list 
> > of rows, and each row has a set of fields. group has to be 
> indexed by 
> > row index and field index. (This is a namedtuple configuration.)
> >
> > The weirdness is that
> >
> > group[0][4]
> 
> Sure.  No trouble there.
> 
> > gets the right answer, but
> >
> > group[[idx][records_idx[label]]],
> > where idx = 0 and records_idx[label]] = 4
> >
> > gets the IndexError.
> 
> group is not involved in the index error.  Just write
> 
>   [idx][records_idx[label]]
> 
> and you'll get the error.  Wrapping that up in group[...] 
> won't make a difference.  In fact, since idx is 0 and 
> records_idx[label]] is 4, you get the same error (for the 
> same reason) by typing
> 
>   [0][4]
> 
> into a Python REPL.  Does it still seem weird?

No, and you also put your finger on (psrt of) the real problem. See the
reply I just sent to MRAB.

 
> This is just another shot at explaining the issue because, 
> sometimes, different words can help.  I thought the message 
> you are replying to (as well as others) explained it well, 
> but it obviously it did not hit the spot.
> 
> <snip>
> -- 
> Ben

No, the spot wasn't getting hit, but it has been now. Thanks for
replying.