[Python] Speed up this code?

[Martin Kelly]

Nope, I tried that and no effect (at least noticeably).

Mike Casaday wrote:
> Not sure if it's faster, but try this:
> 
> def rmlist(original, deletions):
>   return filter(lambda i: i not in deletions, original)
> 
> On May 25, 2006, at 6:10 PM, Martin Kelly wrote:
> 
>> I'm creating a program to calculate all primes numbers in a range of 0 
>> to n, where n is whatever the user wants it to be. I've worked out the 
>> algorithm and it works perfectly and is pretty fast, but the one thing 
>> seriously slowing down the program is the following code:
>>
>> def rmlist(original, deletions):
>>    return [i for i in original if i not in deletions]
>>
>> original will be a list of odd numbers and deletions will be numbers 
>> that are not prime, thus this code will return all items in original 
>> that are not in deletions. For n > 100,000 or so, the program takes a 
>> very long time to run, whereas it's fine for numbers up to 10,000.
>>
>> Does anybody know a faster way to do this? (finding the difference all 
>> items in list a that are not in list b)?
>>
>> Thanks,
>> Martin
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