Creating a list with holes

[Larry Martell]

On Fri, Jan 3, 2014 at 11:07 AM, Chris Angelico <rosuav at gmail.com> wrote:
> On Sat, Jan 4, 2014 at 2:55 AM, Larry Martell <larry.martell at gmail.com> wrote:
>> The use case is that I'm parsing a XML file like this:
>>
>>           <Parameter Name="DefaultVersion">
>>             <Values>
>>               <Value>
>>                 <Default>True</Default>
>>               </Value>
>>             </Values>
>>             <Values>
>>               <Value>
>>                 <Current>False</Current>
>>               </Value>
>>             </Values>
>>             <Values>
>>               <Value>
>>                 <Default>True</Default>
>>                 <Current>False</Current>
>>               </Value>
>>             </Values>
>>             <Values>
>>               <Default>True</Default>
>>             </Values>
>>
>> This is an existing program that is putting the data into a dict. The
>> dict keys are ['DefaultVersion','Default'] and
>> ['DefaultVersion','Current']. These contain lists that have the
>> True/False values.
>
> Are you assigning keys by value, or are you simply appending to the
> lists? It looks to me like you could simply append another element to
> both lists for each <Value> </Value> unit, with the given Default and
> Current if available, or with None for any that aren't set.
> Alternatively, when you get up to the <Value>, append None to each
> list, and then when you see a value, assign to [-1] and overwrite the
> None.

Your last suggestion is what I ended up doing, but I had to key off
the <Values> </Values> unit - I couldn't use <Value> because that
isn't present for ones that have no <Current> - that messed me up for
hours. But it's working now. Thanks all!