[Tutor] Careful Dictionary Building

[Reed O'Brien]

On Dec 28, 2007, at 11:29 AM, doug shawhan wrote:

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

.has_key() is deprecated in 2.6 and goes away in 3.0 IIRC

You should use

record in D

or

D.get(record)


>
> 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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