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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.spark.sql
import java.{lang => jl}
import scala.collection.JavaConverters._
import org.apache.spark.annotation.Experimental
import org.apache.spark.sql.catalyst.expressions._
import org.apache.spark.sql.functions._
import org.apache.spark.sql.types._
/**
* :: Experimental ::
* Functionality for working with missing data in [[DataFrame]]s.
*
* @since 1.3.1
*/
@Experimental
final class DataFrameNaFunctions private[sql](df: DataFrame) {
/**
* Returns a new [[DataFrame]] that drops rows containing any null or NaN values.
*
* @since 1.3.1
*/
def drop(): DataFrame = drop("any", df.columns)
/**
* Returns a new [[DataFrame]] that drops rows containing null or NaN values.
*
* If `how` is "any", then drop rows containing any null or NaN values.
* If `how` is "all", then drop rows only if every column is null or NaN for that row.
*
* @since 1.3.1
*/
def drop(how: String): DataFrame = drop(how, df.columns)
/**
* Returns a new [[DataFrame]] that drops rows containing any null or NaN values
* in the specified columns.
*
* @since 1.3.1
*/
def drop(cols: Array[String]): DataFrame = drop(cols.toSeq)
/**
* (Scala-specific) Returns a new [[DataFrame]] that drops rows containing any null or NaN values
* in the specified columns.
*
* @since 1.3.1
*/
def drop(cols: Seq[String]): DataFrame = drop(cols.size, cols)
/**
* Returns a new [[DataFrame]] that drops rows containing null or NaN values
* in the specified columns.
*
* If `how` is "any", then drop rows containing any null or NaN values in the specified columns.
* If `how` is "all", then drop rows only if every specified column is null or NaN for that row.
*
* @since 1.3.1
*/
def drop(how: String, cols: Array[String]): DataFrame = drop(how, cols.toSeq)
/**
* (Scala-specific) Returns a new [[DataFrame]] that drops rows containing null or NaN values
* in the specified columns.
*
* If `how` is "any", then drop rows containing any null or NaN values in the specified columns.
* If `how` is "all", then drop rows only if every specified column is null or NaN for that row.
*
* @since 1.3.1
*/
def drop(how: String, cols: Seq[String]): DataFrame = {
how.toLowerCase match {
case "any" => drop(cols.size, cols)
case "all" => drop(1, cols)
case _ => throw new IllegalArgumentException(s"how ($how) must be 'any' or 'all'")
}
}
/**
* Returns a new [[DataFrame]] that drops rows containing
* less than `minNonNulls` non-null and non-NaN values.
*
* @since 1.3.1
*/
def drop(minNonNulls: Int): DataFrame = drop(minNonNulls, df.columns)
/**
* Returns a new [[DataFrame]] that drops rows containing
* less than `minNonNulls` non-null and non-NaN values in the specified columns.
*
* @since 1.3.1
*/
def drop(minNonNulls: Int, cols: Array[String]): DataFrame = drop(minNonNulls, cols.toSeq)
/**
* (Scala-specific) Returns a new [[DataFrame]] that drops rows containing less than
* `minNonNulls` non-null and non-NaN values in the specified columns.
*
* @since 1.3.1
*/
def drop(minNonNulls: Int, cols: Seq[String]): DataFrame = {
// Filtering condition:
// only keep the row if it has at least `minNonNulls` non-null and non-NaN values.
val predicate = AtLeastNNonNulls(minNonNulls, cols.map(name => df.resolve(name)))
df.filter(Column(predicate))
}
/**
* Returns a new [[DataFrame]] that replaces null or NaN values in numeric columns with `value`.
*
* @since 1.3.1
*/
def fill(value: Double): DataFrame = fill(value, df.columns)
/**
* Returns a new [[DataFrame]] that replaces null values in string columns with `value`.
*
* @since 1.3.1
*/
def fill(value: String): DataFrame = fill(value, df.columns)
/**
* Returns a new [[DataFrame]] that replaces null or NaN values in specified numeric columns.
* If a specified column is not a numeric column, it is ignored.
*
* @since 1.3.1
*/
def fill(value: Double, cols: Array[String]): DataFrame = fill(value, cols.toSeq)
/**
* (Scala-specific) Returns a new [[DataFrame]] that replaces null or NaN values in specified
* numeric columns. If a specified column is not a numeric column, it is ignored.
*
* @since 1.3.1
*/
def fill(value: Double, cols: Seq[String]): DataFrame = {
val columnEquals = df.sparkSession.sessionState.analyzer.resolver
val projections = df.schema.fields.map { f =>
// Only fill if the column is part of the cols list.
if (f.dataType.isInstanceOf[NumericType] && cols.exists(col => columnEquals(f.name, col))) {
fillCol[Double](f, value)
} else {
df.col(f.name)
}
}
df.select(projections : _*)
}
/**
* Returns a new [[DataFrame]] that replaces null values in specified string columns.
* If a specified column is not a string column, it is ignored.
*
* @since 1.3.1
*/
def fill(value: String, cols: Array[String]): DataFrame = fill(value, cols.toSeq)
/**
* (Scala-specific) Returns a new [[DataFrame]] that replaces null values in
* specified string columns. If a specified column is not a string column, it is ignored.
*
* @since 1.3.1
*/
def fill(value: String, cols: Seq[String]): DataFrame = {
val columnEquals = df.sparkSession.sessionState.analyzer.resolver
val projections = df.schema.fields.map { f =>
// Only fill if the column is part of the cols list.
if (f.dataType.isInstanceOf[StringType] && cols.exists(col => columnEquals(f.name, col))) {
fillCol[String](f, value)
} else {
df.col(f.name)
}
}
df.select(projections : _*)
}
/**
* Returns a new [[DataFrame]] that replaces null values.
*
* The key of the map is the column name, and the value of the map is the replacement value.
* The value must be of the following type:
* `Integer`, `Long`, `Float`, `Double`, `String`, `Boolean`.
* Replacement values are cast to the column data type.
*
* For example, the following replaces null values in column "A" with string "unknown", and
* null values in column "B" with numeric value 1.0.
* {{{
* import com.google.common.collect.ImmutableMap;
* df.na.fill(ImmutableMap.of("A", "unknown", "B", 1.0));
* }}}
*
* @since 1.3.1
*/
def fill(valueMap: java.util.Map[String, Any]): DataFrame = fill0(valueMap.asScala.toSeq)
/**
* (Scala-specific) Returns a new [[DataFrame]] that replaces null values.
*
* The key of the map is the column name, and the value of the map is the replacement value.
* The value must be of the following type: `Int`, `Long`, `Float`, `Double`, `String`, `Boolean`.
* Replacement values are cast to the column data type.
*
* For example, the following replaces null values in column "A" with string "unknown", and
* null values in column "B" with numeric value 1.0.
* {{{
* df.na.fill(Map(
* "A" -> "unknown",
* "B" -> 1.0
* ))
* }}}
*
* @since 1.3.1
*/
def fill(valueMap: Map[String, Any]): DataFrame = fill0(valueMap.toSeq)
/**
* Replaces values matching keys in `replacement` map with the corresponding values.
* Key and value of `replacement` map must have the same type, and
* can only be doubles, strings or booleans.
* If `col` is "*", then the replacement is applied on all string columns or numeric columns.
*
* {{{
* import com.google.common.collect.ImmutableMap;
*
* // Replaces all occurrences of 1.0 with 2.0 in column "height".
* df.replace("height", ImmutableMap.of(1.0, 2.0));
*
* // Replaces all occurrences of "UNKNOWN" with "unnamed" in column "name".
* df.replace("name", ImmutableMap.of("UNKNOWN", "unnamed"));
*
* // Replaces all occurrences of "UNKNOWN" with "unnamed" in all string columns.
* df.replace("*", ImmutableMap.of("UNKNOWN", "unnamed"));
* }}}
*
* @param col name of the column to apply the value replacement
* @param replacement value replacement map, as explained above
*
* @since 1.3.1
*/
def replace[T](col: String, replacement: java.util.Map[T, T]): DataFrame = {
replace[T](col, replacement.asScala.toMap)
}
/**
* Replaces values matching keys in `replacement` map with the corresponding values.
* Key and value of `replacement` map must have the same type, and
* can only be doubles, strings or booleans.
*
* {{{
* import com.google.common.collect.ImmutableMap;
*
* // Replaces all occurrences of 1.0 with 2.0 in column "height" and "weight".
* df.replace(new String[] {"height", "weight"}, ImmutableMap.of(1.0, 2.0));
*
* // Replaces all occurrences of "UNKNOWN" with "unnamed" in column "firstname" and "lastname".
* df.replace(new String[] {"firstname", "lastname"}, ImmutableMap.of("UNKNOWN", "unnamed"));
* }}}
*
* @param cols list of columns to apply the value replacement
* @param replacement value replacement map, as explained above
*
* @since 1.3.1
*/
def replace[T](cols: Array[String], replacement: java.util.Map[T, T]): DataFrame = {
replace(cols.toSeq, replacement.asScala.toMap)
}
/**
* (Scala-specific) Replaces values matching keys in `replacement` map.
* Key and value of `replacement` map must have the same type, and
* can only be doubles, strings or booleans.
* If `col` is "*",
* then the replacement is applied on all string columns , numeric columns or boolean columns.
*
* {{{
* // Replaces all occurrences of 1.0 with 2.0 in column "height".
* df.replace("height", Map(1.0 -> 2.0))
*
* // Replaces all occurrences of "UNKNOWN" with "unnamed" in column "name".
* df.replace("name", Map("UNKNOWN" -> "unnamed")
*
* // Replaces all occurrences of "UNKNOWN" with "unnamed" in all string columns.
* df.replace("*", Map("UNKNOWN" -> "unnamed")
* }}}
*
* @param col name of the column to apply the value replacement
* @param replacement value replacement map, as explained above
*
* @since 1.3.1
*/
def replace[T](col: String, replacement: Map[T, T]): DataFrame = {
if (col == "*") {
replace0(df.columns, replacement)
} else {
replace0(Seq(col), replacement)
}
}
/**
* (Scala-specific) Replaces values matching keys in `replacement` map.
* Key and value of `replacement` map must have the same type, and
* can only be doubles , strings or booleans.
*
* {{{
* // Replaces all occurrences of 1.0 with 2.0 in column "height" and "weight".
* df.replace("height" :: "weight" :: Nil, Map(1.0 -> 2.0));
*
* // Replaces all occurrences of "UNKNOWN" with "unnamed" in column "firstname" and "lastname".
* df.replace("firstname" :: "lastname" :: Nil, Map("UNKNOWN" -> "unnamed");
* }}}
*
* @param cols list of columns to apply the value replacement
* @param replacement value replacement map, as explained above
*
* @since 1.3.1
*/
def replace[T](cols: Seq[String], replacement: Map[T, T]): DataFrame = replace0(cols, replacement)
private def replace0[T](cols: Seq[String], replacement: Map[T, T]): DataFrame = {
if (replacement.isEmpty || cols.isEmpty) {
return df
}
// replacementMap is either Map[String, String] or Map[Double, Double] or Map[Boolean,Boolean]
val replacementMap: Map[_, _] = replacement.head._2 match {
case v: String => replacement
case v: Boolean => replacement
case _ => replacement.map { case (k, v) => (convertToDouble(k), convertToDouble(v)) }
}
// targetColumnType is either DoubleType or StringType or BooleanType
val targetColumnType = replacement.head._1 match {
case _: jl.Double | _: jl.Float | _: jl.Integer | _: jl.Long => DoubleType
case _: jl.Boolean => BooleanType
case _: String => StringType
}
val columnEquals = df.sparkSession.sessionState.analyzer.resolver
val projections = df.schema.fields.map { f =>
val shouldReplace = cols.exists(colName => columnEquals(colName, f.name))
if (f.dataType.isInstanceOf[NumericType] && targetColumnType == DoubleType && shouldReplace) {
replaceCol(f, replacementMap)
} else if (f.dataType == targetColumnType && shouldReplace) {
replaceCol(f, replacementMap)
} else {
df.col(f.name)
}
}
df.select(projections : _*)
}
private def fill0(values: Seq[(String, Any)]): DataFrame = {
// Error handling
values.foreach { case (colName, replaceValue) =>
// Check column name exists
df.resolve(colName)
// Check data type
replaceValue match {
case _: jl.Double | _: jl.Float | _: jl.Integer | _: jl.Long | _: jl.Boolean | _: String =>
// This is good
case _ => throw new IllegalArgumentException(
s"Unsupported value type ${replaceValue.getClass.getName} ($replaceValue).")
}
}
val columnEquals = df.sparkSession.sessionState.analyzer.resolver
val projections = df.schema.fields.map { f =>
values.find { case (k, _) => columnEquals(k, f.name) }.map { case (_, v) =>
v match {
case v: jl.Float => fillCol[Float](f, v)
case v: jl.Double => fillCol[Double](f, v)
case v: jl.Long => fillCol[Long](f, v)
case v: jl.Integer => fillCol[Integer](f, v)
case v: jl.Boolean => fillCol[Boolean](f, v.booleanValue())
case v: String => fillCol[String](f, v)
}
}.getOrElse(df.col(f.name))
}
df.select(projections : _*)
}
/**
* Returns a [[Column]] expression that replaces null value in `col` with `replacement`.
*/
private def fillCol[T](col: StructField, replacement: T): Column = {
val quotedColName = "`" + col.name + "`"
val colValue = col.dataType match {
case DoubleType | FloatType =>
nanvl(df.col(quotedColName), lit(null)) // nanvl only supports these types
case _ => df.col(quotedColName)
}
coalesce(colValue, lit(replacement)).cast(col.dataType).as(col.name)
}
/**
* Returns a [[Column]] expression that replaces value matching key in `replacementMap` with
* value in `replacementMap`, using [[CaseWhen]].
*
* TODO: This can be optimized to use broadcast join when replacementMap is large.
*/
private def replaceCol(col: StructField, replacementMap: Map[_, _]): Column = {
val keyExpr = df.col(col.name).expr
def buildExpr(v: Any) = Cast(Literal(v), keyExpr.dataType)
val branches = replacementMap.flatMap { case (source, target) =>
Seq(buildExpr(source), buildExpr(target))
}.toSeq
new Column(CaseKeyWhen(keyExpr, branches :+ keyExpr)).as(col.name)
}
private def convertToDouble(v: Any): Double = v match {
case v: Float => v.toDouble
case v: Double => v
case v: Long => v.toDouble
case v: Int => v.toDouble
case v => throw new IllegalArgumentException(
s"Unsupported value type ${v.getClass.getName} ($v).")
}
}
