[Tutor] Careful Dictionary Building

[doug shawhan]

*sigh* Ignore folks. I had forgotten about .has_key().



On Dec 28, 2007 11:22 AM, doug shawhan <doug.shawhan at gmail.com> wrote:

> I'm building a dictionary from a list with ~ 1M records.
>
> Each record in the list is itself a list.
> Each record in the list has a line number, (index 0) which I wish to use
> as a dictionary key.
>
> The problem: It is possible for two different records in the list to share
> this line number. If they do, I want to append the record to the value in
> the dictionary.
>
> The obvious (lazy) method of searching for doubled lines requires building
> and parsing a key list for every record. There must be a better way!
>
> dict = {}
> for record in list
>     if record[0] in dict.keys ():
>         dict[ record[0] ].append( record )
>     else:
>         dict[ record[0] ] = [record]
>
> Once you get ~ 80,000 records it starts slowing down pretty badly (I would
> too ...).
>
> Here's hoping there is a really fast, pythonic way of doing this!
>
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