Re: Unique strings array
Re: Unique strings array
- Subject: Re: Unique strings array
- From: Dave DeLong <email@hidden>
- Date: Fri, 11 Mar 2011 18:37:33 -0800
Nope; the whole point of a set is that it doesn't allow duplicates. @"the" is equal to @"the", so it will only be included once. The documentation is quite clear about this.
And while your NSDictionary trick will work, I wouldn't recommend it. It's a misuse of what a dictionary is supposed to be used for.
Dave
Sent from my iPhone
On Mar 11, 2011, at 6:33 PM, Stevo Brock <email@hidden> wrote:
> Unless I'm missing something, if you have aWord1 = @"the" and aWord2 = @"the", they will both get added to the array/set.
>
> You can also use an NSMutableDictionary - just
>
> for (NSString* word in wordsArray)
> [dict setObject:anything forKey:word];
>
> NSArray* uniqueWords = [dict allKeys];
>
> -Stevo
>
>
> On Mar 11, 2011, at 6:19 PM, Dave DeLong wrote:
>
>> Use an NSMutableSet instead. That should have constant lookup time instead of linear (like an array usually is).
>>
>> Dave
>>
>> Sent from my iPhone
>>
>> On Mar 11, 2011, at 6:11 PM, Leonardo <email@hidden> wrote:
>>
>>> Hi,
>>> I have to extract a list of "unique words" from an array of hundred
>>> thousands words and put them into an uniqueWordsArray. I already succeeded
>>> but the task is very very slow because I don't index the uniqueWordsArray.
>>> So my question is: how to index the array and get a fast check?
>>> Actually I do:
>>>
>>> for(NSString *aWord in wordsArray){
>>> if([uniqueWordsArray containsObject:aWord] == NO){
>>> [uniqueWordsArray addObject:aWord];
>>> }
>>> }
>>>
>>> You understand well that the task works fast at the beginning, but it gets
>>> slower and slower at any word added to the uniqueWordsArray.
>>> What's the best way to do that?
>>> Should I use the internal SQLLite database? CoreData? Other?
>>>
>>>
>>> Regards
>>> -- Leonardo
>>>
>>>
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