class LDA extends Estimator[LDAModel] with LDAParams with DefaultParamsWritable
Latent Dirichlet Allocation (LDA), a topic model designed for text documents.
Terminology:
- "term" = "word": an element of the vocabulary
 - "token": instance of a term appearing in a document
 - "topic": multinomial distribution over terms representing some concept
 - "document": one piece of text, corresponding to one row in the input data
 
Original LDA paper (journal version): Blei, Ng, and Jordan. "Latent Dirichlet Allocation." JMLR, 2003.
Input data (featuresCol):
 LDA is given a collection of documents as input data, via the featuresCol parameter.
 Each document is specified as a Vector of length vocabSize, where each entry is the
 count for the corresponding term (word) in the document.  Feature transformers such as
 org.apache.spark.ml.feature.Tokenizer and org.apache.spark.ml.feature.CountVectorizer
 can be useful for converting text to word count vectors.
- Annotations
 - @Since( "1.6.0" )
 - Source
 - LDA.scala
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 - DefaultParamsWritable
 - MLWritable
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        checkpointInterval: IntParam
      
      
      
Param for set checkpoint interval (>= 1) or disable checkpoint (-1).
Param for set checkpoint interval (>= 1) or disable checkpoint (-1). E.g. 10 means that the cache will get checkpointed every 10 iterations. Note: this setting will be ignored if the checkpoint directory is not set in the SparkContext.
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        clear(param: Param[_]): LDA.this.type
      
      
      
Clears the user-supplied value for the input param.
Clears the user-supplied value for the input param.
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        copy(extra: ParamMap): LDA
      
      
      
Creates a copy of this instance with the same UID and some extra params.
Creates a copy of this instance with the same UID and some extra params. Subclasses should implement this method and set the return type properly. See
defaultCopy().- Definition Classes
 - LDA → Estimator → PipelineStage → Params
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        copyValues[T <: Params](to: T, extra: ParamMap = ParamMap.empty): T
      
      
      
Copies param values from this instance to another instance for params shared by them.
Copies param values from this instance to another instance for params shared by them.
This handles default Params and explicitly set Params separately. Default Params are copied from and to
defaultParamMap, and explicitly set Params are copied from and toparamMap. Warning: This implicitly assumes that this Params instance and the target instance share the same set of default Params.- to
 the target instance, which should work with the same set of default Params as this source instance
- extra
 extra params to be copied to the target's
paramMap- returns
 the target instance with param values copied
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        defaultCopy[T <: Params](extra: ParamMap): T
      
      
      
Default implementation of copy with extra params.
Default implementation of copy with extra params. It tries to create a new instance with the same UID. Then it copies the embedded and extra parameters over and returns the new instance.
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        final 
        val
      
      
        docConcentration: DoubleArrayParam
      
      
      
Concentration parameter (commonly named "alpha") for the prior placed on documents' distributions over topics ("theta").
Concentration parameter (commonly named "alpha") for the prior placed on documents' distributions over topics ("theta").
This is the parameter to a Dirichlet distribution, where larger values mean more smoothing (more regularization).
If not set by the user, then docConcentration is set automatically. If set to singleton vector [alpha], then alpha is replicated to a vector of length k in fitting. Otherwise, the docConcentration vector must be length k. (default = automatic)
Optimizer-specific parameter settings:
- EM
- Currently only supports symmetric distributions, so all values in the vector should be the same.
 - Values should be greater than 1.0
 - default = uniformly (50 / k) + 1, where 50/k is common in LDA libraries and +1 follows from Asuncion et al. (2009), who recommend a +1 adjustment for EM.
 
 - Online
- Values should be greater than or equal to 0
 - default = uniformly (1.0 / k), following the implementation from here.
 
 
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        explainParam(param: Param[_]): String
      
      
      
Explains a param.
Explains a param.
- param
 input param, must belong to this instance.
- returns
 a string that contains the input param name, doc, and optionally its default value and the user-supplied value
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Explains all params of this instance.
Explains all params of this instance. See
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        extractParamMap(): ParamMap
      
      
      
extractParamMapwith no extra values.extractParamMapwith no extra values.- Definition Classes
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        extractParamMap(extra: ParamMap): ParamMap
      
      
      
Extracts the embedded default param values and user-supplied values, and then merges them with extra values from input into a flat param map, where the latter value is used if there exist conflicts, i.e., with ordering: default param values less than user-supplied values less than extra.
Extracts the embedded default param values and user-supplied values, and then merges them with extra values from input into a flat param map, where the latter value is used if there exist conflicts, i.e., with ordering: default param values less than user-supplied values less than extra.
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        featuresCol: Param[String]
      
      
      
Param for features column name.
Param for features column name.
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        def
      
      
        fit(dataset: Dataset[_]): LDAModel
      
      
      
Fits a model to the input data.
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        fit(dataset: Dataset[_], paramMaps: Seq[ParamMap]): Seq[LDAModel]
      
      
      
Fits multiple models to the input data with multiple sets of parameters.
Fits multiple models to the input data with multiple sets of parameters. The default implementation uses a for loop on each parameter map. Subclasses could override this to optimize multi-model training.
- dataset
 input dataset
- paramMaps
 An array of parameter maps. These values override any specified in this Estimator's embedded ParamMap.
- returns
 fitted models, matching the input parameter maps
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        def
      
      
        fit(dataset: Dataset[_], paramMap: ParamMap): LDAModel
      
      
      
Fits a single model to the input data with provided parameter map.
Fits a single model to the input data with provided parameter map.
- dataset
 input dataset
- paramMap
 Parameter map. These values override any specified in this Estimator's embedded ParamMap.
- returns
 fitted model
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        fit(dataset: Dataset[_], firstParamPair: ParamPair[_], otherParamPairs: ParamPair[_]*): LDAModel
      
      
      
Fits a single model to the input data with optional parameters.
Fits a single model to the input data with optional parameters.
- dataset
 input dataset
- firstParamPair
 the first param pair, overrides embedded params
- otherParamPairs
 other param pairs. These values override any specified in this Estimator's embedded ParamMap.
- returns
 fitted model
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Optionally returns the user-supplied value of a param.
Optionally returns the user-supplied value of a param.
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Gets the default value of a parameter.
Gets the default value of a parameter.
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        def
      
      
        getDocConcentration: Array[Double]
      
      
      
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        getFeaturesCol: String
      
      
      
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        getK: Int
      
      
      
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        getKeepLastCheckpoint: Boolean
      
      
      
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        getLearningDecay: Double
      
      
      
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        getMaxIter: Int
      
      
      
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        def
      
      
        getOldDocConcentration: Vector
      
      
      
Get docConcentration used by spark.mllib LDA
Get docConcentration used by spark.mllib LDA
- Attributes
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        def
      
      
        getOldTopicConcentration: Double
      
      
      
Get topicConcentration used by spark.mllib LDA
Get topicConcentration used by spark.mllib LDA
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        getOptimizeDocConcentration: Boolean
      
      
      
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        getOptimizer: String
      
      
      
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Gets the value of a param in the embedded param map or its default value.
Gets the value of a param in the embedded param map or its default value. Throws an exception if neither is set.
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        getParam(paramName: String): Param[Any]
      
      
      
Gets a param by its name.
Gets a param by its name.
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        getSeed: Long
      
      
      
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        getSubsamplingRate: Double
      
      
      
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Tests whether the input param has a default value set.
Tests whether the input param has a default value set.
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Tests whether this instance contains a param with a given name.
Tests whether this instance contains a param with a given name.
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Checks whether a param is explicitly set or has a default value.
Checks whether a param is explicitly set or has a default value.
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Checks whether a param is explicitly set.
Checks whether a param is explicitly set.
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        isTraceEnabled(): Boolean
      
      
      
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        final 
        val
      
      
        k: IntParam
      
      
      
Param for the number of topics (clusters) to infer.
Param for the number of topics (clusters) to infer. Must be > 1. Default: 10.
- Definition Classes
 - LDAParams
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        final 
        val
      
      
        keepLastCheckpoint: BooleanParam
      
      
      
For EM optimizer only: optimizer = "em".
For EM optimizer only: optimizer = "em".
If using checkpointing, this indicates whether to keep the last checkpoint. If false, then the checkpoint will be deleted. Deleting the checkpoint can cause failures if a data partition is lost, so set this bit with care. Note that checkpoints will be cleaned up via reference counting, regardless.
See
DistributedLDAModel.getCheckpointFilesfor getting remaining checkpoints andDistributedLDAModel.deleteCheckpointFilesfor removing remaining checkpoints.Default: true
- Definition Classes
 - LDAParams
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 - @Since( "2.0.0" )
 
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        final 
        val
      
      
        learningDecay: DoubleParam
      
      
      
For Online optimizer only: optimizer = "online".
For Online optimizer only: optimizer = "online".
Learning rate, set as an exponential decay rate. This should be between (0.5, 1.0] to guarantee asymptotic convergence. This is called "kappa" in the Online LDA paper (Hoffman et al., 2010). Default: 0.51, based on Hoffman et al.
- Definition Classes
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        final 
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        learningOffset: DoubleParam
      
      
      
For Online optimizer only: optimizer = "online".
For Online optimizer only: optimizer = "online".
A (positive) learning parameter that downweights early iterations. Larger values make early iterations count less. This is called "tau0" in the Online LDA paper (Hoffman et al., 2010) Default: 1024, following Hoffman et al.
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        maxIter: IntParam
      
      
      
Param for maximum number of iterations (>= 0).
Param for maximum number of iterations (>= 0).
- Definition Classes
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        ne(arg0: AnyRef): Boolean
      
      
      
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        notify(): Unit
      
      
      
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        final 
        val
      
      
        optimizeDocConcentration: BooleanParam
      
      
      
For Online optimizer only (currently): optimizer = "online".
For Online optimizer only (currently): optimizer = "online".
Indicates whether the docConcentration (Dirichlet parameter for document-topic distribution) will be optimized during training. Setting this to true will make the model more expressive and fit the training data better. Default: false
- Definition Classes
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        final 
        val
      
      
        optimizer: Param[String]
      
      
      
Optimizer or inference algorithm used to estimate the LDA model.
Optimizer or inference algorithm used to estimate the LDA model. Currently supported (case-insensitive):
- "online": Online Variational Bayes (default)
 - "em": Expectation-Maximization
 
For details, see the following papers:
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        lazy val
      
      
        params: Array[Param[_]]
      
      
      
Returns all params sorted by their names.
Returns all params sorted by their names. The default implementation uses Java reflection to list all public methods that have no arguments and return Param.
- Definition Classes
 - Params
 - Note
 Developer should not use this method in constructor because we cannot guarantee that this variable gets initialized before other params.
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        def
      
      
        save(path: String): Unit
      
      
      
Saves this ML instance to the input path, a shortcut of
write.save(path).Saves this ML instance to the input path, a shortcut of
write.save(path).- Definition Classes
 - MLWritable
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        final 
        val
      
      
        seed: LongParam
      
      
      
Param for random seed.
Param for random seed.
- Definition Classes
 - HasSeed
 
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        final 
        def
      
      
        set(paramPair: ParamPair[_]): LDA.this.type
      
      
      
Sets a parameter in the embedded param map.
Sets a parameter in the embedded param map.
- Attributes
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        final 
        def
      
      
        set(param: String, value: Any): LDA.this.type
      
      
      
Sets a parameter (by name) in the embedded param map.
Sets a parameter (by name) in the embedded param map.
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        final 
        def
      
      
        set[T](param: Param[T], value: T): LDA.this.type
      
      
      
Sets a parameter in the embedded param map.
Sets a parameter in the embedded param map.
- Definition Classes
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        def
      
      
        setCheckpointInterval(value: Int): LDA.this.type
      
      
      
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        final 
        def
      
      
        setDefault(paramPairs: ParamPair[_]*): LDA.this.type
      
      
      
Sets default values for a list of params.
Sets default values for a list of params.
Note: Java developers should use the single-parameter
setDefault. Annotating this with varargs can cause compilation failures due to a Scala compiler bug. See SPARK-9268.- paramPairs
 a list of param pairs that specify params and their default values to set respectively. Make sure that the params are initialized before this method gets called.
- Attributes
 - protected
 - Definition Classes
 - Params
 
 - 
      
      
      
        
      
    
      
        final 
        def
      
      
        setDefault[T](param: Param[T], value: T): LDA.this.type
      
      
      
Sets a default value for a param.
 - 
      
      
      
        
      
    
      
        
        def
      
      
        setDocConcentration(value: Double): LDA.this.type
      
      
      
- Annotations
 - @Since( "1.6.0" )
 
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        def
      
      
        setDocConcentration(value: Array[Double]): LDA.this.type
      
      
      
- Annotations
 - @Since( "1.6.0" )
 
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        def
      
      
        setFeaturesCol(value: String): LDA.this.type
      
      
      
The features for LDA should be a
Vectorrepresenting the word counts in a document.The features for LDA should be a
Vectorrepresenting the word counts in a document. The vector should be of length vocabSize, with counts for each term (word).- Annotations
 - @Since( "1.6.0" )
 
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        def
      
      
        setK(value: Int): LDA.this.type
      
      
      
- Annotations
 - @Since( "1.6.0" )
 
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        def
      
      
        setKeepLastCheckpoint(value: Boolean): LDA.this.type
      
      
      
- Annotations
 - @Since( "2.0.0" )
 
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        def
      
      
        setLearningDecay(value: Double): LDA.this.type
      
      
      
- Annotations
 - @Since( "1.6.0" )
 
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        def
      
      
        setLearningOffset(value: Double): LDA.this.type
      
      
      
- Annotations
 - @Since( "1.6.0" )
 
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        def
      
      
        setMaxIter(value: Int): LDA.this.type
      
      
      
- Annotations
 - @Since( "1.6.0" )
 
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        def
      
      
        setOptimizeDocConcentration(value: Boolean): LDA.this.type
      
      
      
- Annotations
 - @Since( "1.6.0" )
 
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        def
      
      
        setOptimizer(value: String): LDA.this.type
      
      
      
- Annotations
 - @Since( "1.6.0" )
 
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        def
      
      
        setSeed(value: Long): LDA.this.type
      
      
      
- Annotations
 - @Since( "1.6.0" )
 
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        def
      
      
        setSubsamplingRate(value: Double): LDA.this.type
      
      
      
- Annotations
 - @Since( "1.6.0" )
 
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        def
      
      
        setTopicConcentration(value: Double): LDA.this.type
      
      
      
- Annotations
 - @Since( "1.6.0" )
 
 - 
      
      
      
        
      
    
      
        
        def
      
      
        setTopicDistributionCol(value: String): LDA.this.type
      
      
      
- Annotations
 - @Since( "1.6.0" )
 
 - 
      
      
      
        
      
    
      
        final 
        val
      
      
        subsamplingRate: DoubleParam
      
      
      
For Online optimizer only: optimizer = "online".
For Online optimizer only: optimizer = "online".
Fraction of the corpus to be sampled and used in each iteration of mini-batch gradient descent, in range (0, 1].
Note that this should be adjusted in synch with
LDA.maxIterso the entire corpus is used. Specifically, set both so that maxIterations * miniBatchFraction greater than or equal to 1.Note: This is the same as the
miniBatchFractionparameter in org.apache.spark.mllib.clustering.OnlineLDAOptimizer.Default: 0.05, i.e., 5% of total documents.
- Definition Classes
 - LDAParams
 - Annotations
 - @Since( "1.6.0" )
 
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        final 
        val
      
      
        supportedOptimizers: Array[String]
      
      
      
Supported values for Param optimizer.
Supported values for Param optimizer.
- Definition Classes
 - LDAParams
 - Annotations
 - @Since( "1.6.0" )
 
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        final 
        def
      
      
        synchronized[T0](arg0: ⇒ T0): T0
      
      
      
- Definition Classes
 - AnyRef
 
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        def
      
      
        toString(): String
      
      
      
- Definition Classes
 - Identifiable → AnyRef → Any
 
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        final 
        val
      
      
        topicConcentration: DoubleParam
      
      
      
Concentration parameter (commonly named "beta" or "eta") for the prior placed on topics' distributions over terms.
Concentration parameter (commonly named "beta" or "eta") for the prior placed on topics' distributions over terms.
This is the parameter to a symmetric Dirichlet distribution.
Note: The topics' distributions over terms are called "beta" in the original LDA paper by Blei et al., but are called "phi" in many later papers such as Asuncion et al., 2009.
If not set by the user, then topicConcentration is set automatically. (default = automatic)
Optimizer-specific parameter settings:
- EM
- Value should be greater than 1.0
 - default = 0.1 + 1, where 0.1 gives a small amount of smoothing and +1 follows Asuncion et al. (2009), who recommend a +1 adjustment for EM.
 
 - Online
- Value should be greater than or equal to 0
 - default = (1.0 / k), following the implementation from here.
 
 
- Definition Classes
 - LDAParams
 - Annotations
 - @Since( "1.6.0" )
 
 - EM
 - 
      
      
      
        
      
    
      
        final 
        val
      
      
        topicDistributionCol: Param[String]
      
      
      
Output column with estimates of the topic mixture distribution for each document (often called "theta" in the literature).
Output column with estimates of the topic mixture distribution for each document (often called "theta" in the literature). Returns a vector of zeros for an empty document.
This uses a variational approximation following Hoffman et al. (2010), where the approximate distribution is called "gamma." Technically, this method returns this approximation "gamma" for each document.
- Definition Classes
 - LDAParams
 - Annotations
 - @Since( "1.6.0" )
 
 - 
      
      
      
        
      
    
      
        
        def
      
      
        transformSchema(schema: StructType): StructType
      
      
      
Check transform validity and derive the output schema from the input schema.
Check transform validity and derive the output schema from the input schema.
We check validity for interactions between parameters during
transformSchemaand raise an exception if any parameter value is invalid. Parameter value checks which do not depend on other parameters are handled byParam.validate().Typical implementation should first conduct verification on schema change and parameter validity, including complex parameter interaction checks.
- Definition Classes
 - LDA → PipelineStage
 - Annotations
 - @Since( "1.6.0" )
 
 - 
      
      
      
        
      
    
      
        
        def
      
      
        transformSchema(schema: StructType, logging: Boolean): StructType
      
      
      
:: DeveloperApi ::
:: DeveloperApi ::
Derives the output schema from the input schema and parameters, optionally with logging.
This should be optimistic. If it is unclear whether the schema will be valid, then it should be assumed valid until proven otherwise.
- Attributes
 - protected
 - Definition Classes
 - PipelineStage
 - Annotations
 - @DeveloperApi()
 
 - 
      
      
      
        
      
    
      
        
        val
      
      
        uid: String
      
      
      
An immutable unique ID for the object and its derivatives.
An immutable unique ID for the object and its derivatives.
- Definition Classes
 - LDA → Identifiable
 - Annotations
 - @Since( "1.6.0" )
 
 - 
      
      
      
        
      
    
      
        
        def
      
      
        validateAndTransformSchema(schema: StructType): StructType
      
      
      
Validates and transforms the input schema.
Validates and transforms the input schema.
- schema
 input schema
- returns
 output schema
- Attributes
 - protected
 - Definition Classes
 - LDAParams
 
 - 
      
      
      
        
      
    
      
        final 
        def
      
      
        wait(): Unit
      
      
      
- Definition Classes
 - AnyRef
 - Annotations
 - @throws( ... )
 
 - 
      
      
      
        
      
    
      
        final 
        def
      
      
        wait(arg0: Long, arg1: Int): Unit
      
      
      
- Definition Classes
 - AnyRef
 - Annotations
 - @throws( ... )
 
 - 
      
      
      
        
      
    
      
        final 
        def
      
      
        wait(arg0: Long): Unit
      
      
      
- Definition Classes
 - AnyRef
 - Annotations
 - @throws( ... ) @native()
 
 - 
      
      
      
        
      
    
      
        
        def
      
      
        write: MLWriter
      
      
      
Returns an
MLWriterinstance for this ML instance.Returns an
MLWriterinstance for this ML instance.- Definition Classes
 - DefaultParamsWritable → MLWritable
 
 
Inherited from DefaultParamsWritable
Inherited from MLWritable
Inherited from LDAParams
Inherited from HasCheckpointInterval
Inherited from HasSeed
Inherited from HasMaxIter
Inherited from HasFeaturesCol
Inherited from PipelineStage
Inherited from Logging
Inherited from Params
Inherited from Serializable
Inherited from Serializable
Inherited from Identifiable
Inherited from AnyRef
Inherited from Any
Parameters
A list of (hyper-)parameter keys this algorithm can take. Users can set and get the parameter values through setters and getters, respectively.
Members
Parameter setters
Parameter getters
(expert-only) Parameters
A list of advanced, expert-only (hyper-)parameter keys this algorithm can take. Users can set and get the parameter values through setters and getters, respectively.