documented GnocchiSession (bigdatagenomics#28)

gnocchi-core/src/main/scala/org/bdgenomics/gnocchi/sql/GnocchiSession.scala

@@ -21,11 +21,29 @@ object GnocchiSession {
     new GnocchiSession(sc)
 }
 
+/**
+ * The GnocchiSession provides functions on top of a SparkContext for loading and
+ * analyzing genome data.
+ *
+ * @param sc The SparkContext to wrap.
+ */
 class GnocchiSession(@transient val sc: SparkContext) extends Serializable with Logging {
 
   val sparkSession = SparkSession.builder().getOrCreate()
   import sparkSession.implicits._
 
+  /**
+   * Returns a filtered Dataset of CalledVariant objects, where all values with
+   * fewer samples than the mind threshold are filtered out.
+   *
+   * @param genotypes The Dataset of CalledVariant objects to filter on
+   * @param mind The percentage threshold of samples to have filled in; values
+   *             with fewer samples will be removed in this operation.
+   * @param ploidy The number of sets of chromosomes
+   *
+   * @return Returns an updated Dataset with values removed, as specified by the
+   *         filtering
+   */
   def filterSamples(genotypes: Dataset[CalledVariant], mind: Double, ploidy: Double): Dataset[CalledVariant] = {
     require(mind >= 0.0 && mind <= 1.0, "`mind` value must be between 0.0 to 1.0 inclusive.")
     val sampleIds = genotypes.first.samples.map(x => x.sampleID)
@@ -50,6 +68,19 @@ class GnocchiSession(@transient val sc: SparkContext) extends Serializable with
     genotypes.drop("samples").join(filteredDF, "uniqueID").as[CalledVariant]
   }
 
+  /**
+   * Returns a filtered Dataset of CalledVariant objects, where all variants with
+   * values less than the specified geno or maf threshold are filtered out.
+   *
+   * @param genotypes The Dataset of CalledVariant objects to filter on
+   * @param geno The percentage threshold for geno values for each CalledVariant
+   *             object
+   * @param maf The percentage threshold for Minor Allele Frequency for each
+   *            CalledVariant object
+   *
+   * @return Returns an updated Dataset with values removed, as specified by the
+   *         filtering
+   */
   def filterVariants(genotypes: Dataset[CalledVariant], geno: Double, maf: Double): Dataset[CalledVariant] = {
     require(maf >= 0.0 && maf <= 1.0, "`maf` value must be between 0.0 to 1.0 inclusive.")
     require(geno >= 0.0 && geno <= 1.0, "`geno` value must be between 0.0 to 1.0 inclusive.")
@@ -62,6 +93,15 @@ class GnocchiSession(@transient val sc: SparkContext) extends Serializable with
     mafFiltered
   }
 
+  /**
+   * Returns a modified Dataset of CalledVariant objects, where any value with a
+   * maf > 0.5 is recoded. The recoding is specified as flipping the referenceAllele
+   * and alternateAllele when the frequency of alt is greater than that of ref.
+   *
+   * @param genotypes The Dataset of CalledVariant objects to recode
+   *
+   * @return Returns an updated Dataset that has been recoded
+   */
   def recodeMajorAllele(genotypes: Dataset[CalledVariant]): Dataset[CalledVariant] = {
     val minorAlleleF = genotypes.map(x => (x.uniqueID, x.maf)).toDF("uniqueID", "maf")
     val genoWithMaf = genotypes.join(minorAlleleF, "uniqueID")
@@ -117,6 +157,23 @@ class GnocchiSession(@transient val sc: SparkContext) extends Serializable with
     }).toDS
   }
 
+  /**
+   * Returns a map of phenotype name to phenotype object, which is loaded from
+   * a file, specified by phenotypesPath
+   *
+   * @param phenotypesPath A string specifying the location in the file system
+   *                       of the phenotypes file to load in.
+   * @param primaryID The primary sample ID
+   * @param phenoName The primary phenotype
+   * @param delimiter The delimiter used in the input file
+   * @param covarPath Optional parameter specifying the location in the file
+   *                  system of the covariants file
+   * @param covarNames Optional paramter specifying the names of the covariants
+   *                   detailed in the covariants file
+   * @param covarDelimiter The delimiter used in the covariants file
+   *
+   * @return A Map of phenotype name to Phenotype object
+   */
   def loadPhenotypes(phenotypesPath: String,
                      primaryID: String,
                      phenoName: String,
@@ -184,4 +241,4 @@ class GnocchiSession(@transient val sc: SparkContext) extends Serializable with
 
     phenoCovarDF.withColumn("phenoName", lit(phenoName)).as[Phenotype].collect().map(x => (x.sampleId, x)).toMap
   }
-}
+}