Open Radar

 
27-Aug-2013 03:04 PM Oliver Mason:
Summary:
The "possibleTagsAtIndex" method of the NSLinguisticTagger class does not return scores.

Steps to Reproduce:
Execute the attached code. This takes a single (English) sentence, analyses it, and logs the results.

Expected Results:
Apart from the list of possible tags, a list containing the respective likelihood scores should also be returned.

2013-08-27 14:42:15.281 NLPlayground[29985:303] train: Noun
2013-08-27 14:42:15.282 NLPlayground[29985:303] poss: (
    Noun,
    Verb
); scores: (**HERE SHOULD BE TWO NSVALUE OBJECTS CONTAINING SCORES**)

Actual Results:

2013-08-27 14:42:15.281 NLPlayground[29985:303] train: Noun
2013-08-27 14:42:15.282 NLPlayground[29985:303] poss: (
    Noun,
    Verb
); scores: (null)

Regression:
This issue does not seem to affect tagging performance.

Notes:
The salient parts of the source code are:


        NSString *question = @"When is the next train to Aberystwyth?";
        NSLinguisticTaggerOptions options = NSLinguisticTaggerOmitWhitespace | NSLinguisticTaggerOmitPunctuation | NSLinguisticTaggerJoinNames;
        NSLinguisticTagger *tagger = [[NSLinguisticTagger alloc] initWithTagSchemes: [NSLinguisticTagger availableTagSchemesForLanguage:@"en"] options:options];
        tagger.string = question;
        [tagger enumerateTagsInRange:NSMakeRange(0, [question length]) scheme:NSLinguisticTagSchemeNameTypeOrLexicalClass options:options usingBlock:^(NSString *tag, NSRange tokenRange, NSRange sentenceRange, BOOL *stop) {
            NSString *token = [question substringWithRange:tokenRange];
            NSLog(@"%@: %@", token, tag);
            NSArray *scores = nil;
            NSArray *poss = [tagger possibleTagsAtIndex:tokenRange.location scheme:NSLinguisticTagSchemeLexicalClass tokenRange:&tokenRange sentenceRange:&sentenceRange scores:&scores];
            NSLog(@"poss: %@; scores: %@",poss,scores);
        }];


The final three lines (starting from the NSArray *scores declaration) are the relevant parts.