My other works

[http://leverdeterre.github.io] (http://leverdeterre.github.io)

PermissiveResearch

An iOS search engine that allows mistakes in the searched element in huge data. Many developpers would have executed a fectch request on a CoreData database or a predicate to filter on a NSArray.

PermissiveResearch is a alternative to simplify the search step. Advantages :

• No more problems with CoreData (context/thread),
• Performances,
• 100% resusable for each projects that need to perform analysis in huge data,
• Search algorithm are easy customizable,
• 3 algorithms already implemented,

Performances (on iphone4, searchig in 5000 objects 4 properties)

Type of search	time (ms)	data structure
Exact search	200	Using predicates
Exact search	2800	Using PermissiveResearch (ExactScoringOperation*)
Exact search	100	Using PermissiveResearch (HeuristicScoringOperation*)
Exact search	700	Using PermissiveResearch (HeurexactScoringOperation*)
Tolerated search	impossible..	Using predicates
Tolerated search	2800	Using PermissiveResearch (ExactScoringOperation*)
Tolerated search	100	Using PermissiveResearch (HeuristicScoringOperation*)
Tolerated search	700	Using PermissiveResearch (HeurexactScoringOperation*)

• ExactScoringOperation : Make a complex and total analysis,
• HeuristicScoringOperation : Scan using fragments (default size 3),
• HeurexactScoringOperation : Scan using fragments (default size 3), then make a complex and total analysis of the best pre-selected objects.

Algorithms

It's a custom implementation of the [Smith-Waterman algorithm][1]. The purpose of the algorithm is to obtain the optimum local alignment. A similarity matrix is use to tolerate errors. [1]: http://en.wikipedia.org/wiki/Smith–Waterman_algorithm

Shared instance

[[PermissiveResearchDatabase sharedDatabase] setDatasource:self];

Datasource methods to fill your search database

-(void)rebuildDatabase

- (void)addObject:(id)obj forKey:(NSString *)key;
- (void)addObjects:(NSArray *)obj forKey:(NSString *)key;
- (void)addObjects:(NSArray *)objs forKeys:(NSArray *)keys;
- (void)addObjects:(NSArray *)objs forKeyPaths:(NSArray *)KeyPaths;

- (void)addManagedObject:(NSManagedObject *)obj forKey:(NSString *)key;
- (void)addManagedObjects:(NSArray *)objs forKey:(NSString *)key;
- (void)addManagedObjects:(NSArray *)objs forKeys:(NSArray *)keys;
- (void)addManagedObjects:(NSArray *)objs forKeyPaths:(NSArray *)KeyPaths;

Example :

///PermissiveResearchDatabase datasource
-(void)rebuildDatabase
{
    NSString *jsonPath = [[NSBundle mainBundle] pathForResource:@"data5000"
                                                         ofType:@"json"];
    NSData *data = [NSData dataWithContentsOfFile:jsonPath];
    NSError *error = nil;
    id json = [NSJSONSerialization JSONObjectWithData:data
                                              options:kNilOptions
                                                error:&error];
    
    [[PermissiveResearchDatabase sharedDatabase] addObjects:json forKeyPaths:@[@"name",@"gender",@"company",@"email"]];
    self.searchedList = json;
}

Datasource method to customize scoring methods

-(NSInteger)customCostForEvent:(ScoringEvent)event

Example (default values) :

-(NSInteger)customCostForEvent:(ScoringEvent)event
{
    switch (event) {
        case ScoringEventPerfectMatch:
            return 2;
            break;
           
        case ScoringEventNotPerfectMatchKeyboardAnalyseHelp:
            return 1;
            break;
            
        case ScoringEventNotPerfectBecauseOfAccents:
            return 2;
            break;
            
        case ScoringEventLetterAddition:
            return -1;
            break;
            
        default:
            break;
    }
    
    return NSNotFound;
}

Easy search operation using PermissiveResearch delegate

[[PermissiveResearchDatabase sharedDatabase] setDelegate:self];
[[PermissiveResearchDatabase sharedDatabase] searchString:searchedString withOperation:ScoringOperationTypeExact];
    
#pragma mark PermissiveResearchDelegate

-(void)searchCompletedWithResults:(NSArray *)results
{
    dispatch_async(dispatch_get_main_queue(), ^{
        self.findedElements = results;
        [self.tableView reloadData];
    });
}

Create your first search operation

    [[ScoringOperationQueue mainQueue] cancelAllOperations]
    HeuristicScoringOperation *ope = [[HeuristicScoringOperation alloc] init];
    ope.searchedString = searchedString;
    
    SearchCompletionBlock block = ^(NSArray *results) {
        dispatch_async(dispatch_get_main_queue(), ^{
            self.findedElements = results;
            NSLog(@"finded elements %@", results);
        });
    };
    
    [ope setCustomCompletionBlock:block];
    [[ScoringOperationQueue mainQueue] addOperation:ope];

Actualy 3 operations are available, usage depends on the performance you need.

Algorithms complexities are very differents. HeuristicScoringOperation < HeurexactScoringOperation << ExactScoringOperation

ExactScoringOperation
HeuristicScoringOperation
HeurexactScoringOperation

TODO

• Tolerate keyboard errors, very proximal letters can be tolerate.