OOConcreteProbabilitySet Class Reference

Inheritance diagram for OOConcreteProbabilitySet:

Collaboration diagram for OOConcreteProbabilitySet:

Instance Methods
(id)	- initWithObjects:weights:count: [implementation]
(void)	- dealloc [implementation]
(NSDictionary *)	- propertyListRepresentation [implementation]
(NSUInteger)	- count [implementation]
(id)	- privObjectForWeight: [implementation]
(id)	- randomObject [implementation]
(float)	- weightForObject: [implementation]
(float)	- sumOfWeights [implementation]
(NSArray *)	- allObjects [implementation]
(NSEnumerator *)	- objectEnumerator [implementation]
(id)	- privObjectAtIndex: [implementation]
(id)	- mutableCopyWithZone: [implementation]
Instance Methods inherited from OOProbabilitySet
(id)	- init
(id)	- initWithPropertyListRepresentation:
(id)	- initPriv [implementation]
(NSString *)	- descriptionComponents [implementation]
(id)	- copyWithZone: [implementation]
(BOOL)	- containsObject:
(float)	- probabilityForObject:

Private Attributes
NSUInteger	_count
id *	_objects
float *	_cumulativeWeights
float	_sumOfWeights

Additional Inherited Members
Class Methods inherited from OOProbabilitySet
(id)	+ probabilitySet
(id)	+ probabilitySetWithObjects:weights:count:
(id)	+ probabilitySetWithPropertyListRepresentation:

Detailed Description

Definition at line 92 of file OOProbabilitySet.m.

Method Documentation

allObjects

- (NSArray *) allObjects

implementation

Reimplemented from OOProbabilitySet.

Definition at line 458 of file OOProbabilitySet.m.

{
    return [NSArray arrayWithObjects:_objects count:_count];
}
 

count

- (NSUInteger) count

implementation

Reimplemented from OOProbabilitySet.

Definition at line 458 of file OOProbabilitySet.m.

{
    return _count;
}
 

dealloc

- (void) dealloc

implementation

Definition at line 458 of file OOProbabilitySet.m.

{
    NSUInteger              i = 0;
    
    if (_objects != NULL)
    {
        for (i = 0; i < _count; ++i)
        {
            [_objects[i] release];
        }
        free(_objects);
        _objects = NULL;
    }
    
    if (_cumulativeWeights != NULL)
    {
        free(_cumulativeWeights);
        _cumulativeWeights = NULL;
    }
    
    [super dealloc];
}
 

initWithObjects:weights:count:

- (id) initWithObjects: (id *)  objects weights: (float *)  weights count: (NSUInteger)  count

implementation

Reimplemented from OOProbabilitySet.

Definition at line 458 of file OOProbabilitySet.m.

{
    NSUInteger              i = 0;
    float                   cuWeight = 0.0f;
    
    assert(count > 1 && objects != NULL && weights != NULL);
    
    if ((self = [super initPriv]))
    {
        // Allocate arrays
        _objects = malloc(sizeof *objects * count);
        _cumulativeWeights = malloc(sizeof *_cumulativeWeights * count);
        if (_objects == NULL || _cumulativeWeights == NULL)
        {
            [self release];
            return nil;
        }
        
        // Fill in arrays, retain objects, add up weights.
        for (i = 0; i != count; ++i)
        {
            _objects[i] = [objects[i] retain];
            cuWeight += weights[i];
            _cumulativeWeights[i] = cuWeight;
        }
        _count = count;
        _sumOfWeights = cuWeight;
    }
    
    return self;
}
 

mutableCopyWithZone:

- (id) mutableCopyWithZone: (NSZone *)  zone

implementation

Reimplemented from OOProbabilitySet.

Definition at line 458 of file OOProbabilitySet.m.

{
    id                      result = nil;
    float                   *weights = NULL;
    NSUInteger              i = 0;
    float                   weight = 0.0f, sum = 0.0f;
    
    // Convert cumulative weights to "plain" weights.
    weights = malloc(sizeof *weights * _count);
    if (weights == NULL)  return nil;
    
    for (i = 0; i < _count; ++i)
    {
        weight = _cumulativeWeights[i];
        weights[i] = weight - sum;
        sum += weights[i];
    }
    
    result = [[OOConcreteMutableProbabilitySet allocWithZone:zone] initWithObjects:_objects weights:weights count:_count];
    free(weights);
    
    return result;
}
 

objectEnumerator

- (NSEnumerator *) objectEnumerator

implementation

Reimplemented from OOProbabilitySet.

Definition at line 458 of file OOProbabilitySet.m.

{
    return [[[OOProbabilitySetEnumerator alloc] initWithEnumerable:self] autorelease];
}
 

privObjectAtIndex:

- (id) privObjectAtIndex: (NSUInteger)  index

implementation

Reimplemented from <OOProbabilitySetEnumerable>.

Definition at line 458 of file OOProbabilitySet.m.

{
    return (index < _count) ? _objects[index] : nil;
}
 

privObjectForWeight:

- (id) privObjectForWeight: (float)  target

implementation

Definition at line 458 of file OOProbabilitySet.m.

{
    /*  Select an object at random. This is a binary search in the cumulative
        weights array. Since weights of zero are allowed, there may be several
        objects with the same cumulative weight, in which case we select the
        leftmost, i.e. the one where the delta is non-zero.
    */
    
    NSUInteger                  low = 0, high = _count - 1, idx = 0;
    float                       weight = 0.0f;
    
    while (low < high)
    {
        idx = (low + high) / 2;
        weight = _cumulativeWeights[idx];
        if (weight > target)
        {
            if (EXPECT_NOT(idx == 0))  break;
            high = idx - 1;
        }
        else if (weight < target)  low = idx + 1;
        else break;
    }
    
    if (weight > target)
    {
        while (idx > 0 && _cumulativeWeights[idx - 1] >= target)  --idx;
    }
    else
    {
        while (idx < (_count - 1) && _cumulativeWeights[idx] < target)  ++idx;
    }
    
    assert(idx < _count);
    id result = _objects[idx];
    return result;
}
 

propertyListRepresentation

- (NSDictionary *) propertyListRepresentation

implementation

Reimplemented from OOProbabilitySet.

Definition at line 458 of file OOProbabilitySet.m.

{
    NSArray                 *objects = nil;
    NSMutableArray          *weights = nil;
    float                   cuWeight = 0.0f, sum = 0.0f;
    NSUInteger              i = 0;
    
    objects = [NSArray arrayWithObjects:_objects count:_count];
    weights = [NSMutableArray arrayWithCapacity:_count];
    for (i = 0; i < _count; ++i)
    {
        cuWeight = _cumulativeWeights[i];
        [weights oo_addFloat:cuWeight - sum];
        sum = cuWeight;
    }
    
    return [NSDictionary dictionaryWithObjectsAndKeys:
            objects, kObjectsKey,
            [[weights copy] autorelease], kWeightsKey,
            nil];
}
 

randomObject

- (id) randomObject

implementation

Reimplemented from OOProbabilitySet.

Definition at line 458 of file OOProbabilitySet.m.

{
    if (_sumOfWeights <= 0.0f)  return nil;
    return [self privObjectForWeight:randf() * _sumOfWeights];
}
 

sumOfWeights

- (float) sumOfWeights

implementation

Reimplemented from OOProbabilitySet.

Definition at line 458 of file OOProbabilitySet.m.

{
    return _sumOfWeights;
}
 

weightForObject:

- (float) weightForObject: (id)  object

implementation

Reimplemented from OOProbabilitySet.

Definition at line 458 of file OOProbabilitySet.m.

{
    NSUInteger                  i;
    
    // Can't have nil in collection.
    if (object == nil)  return -1.0f;
    
    // Perform linear search, then get weight by subtracting cumulative weight from cumulative weight to left.
    for (i = 0; i < _count; ++i)
    {
        if ([_objects[i] isEqual:object])
        {
            float leftWeight = (i != 0) ? _cumulativeWeights[i - 1] : 0.0f;
            return _cumulativeWeights[i] - leftWeight;
        }
    }
    
    // If we got here, object not found.
    return -1.0f;
}
 

Member Data Documentation

_count

- (NSUInteger) _count

private

Definition at line 96 of file OOProbabilitySet.m.

_cumulativeWeights

- (float*) _cumulativeWeights

private

Definition at line 98 of file OOProbabilitySet.m.

_objects

- (id*) _objects

private

Definition at line 97 of file OOProbabilitySet.m.

_sumOfWeights

- (float) _sumOfWeights

private

Definition at line 99 of file OOProbabilitySet.m.

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The documentation for this class was generated from the following file:

• src/Core/OOProbabilitySet.m